diff --git a/algorithm/category.json b/algorithm/category.json
index b4788499..a6e1588d 100644
--- a/algorithm/category.json
+++ b/algorithm/category.json
@@ -30,7 +30,8 @@
       "bubble": "Bubble Sort",
       "quick": "Quicksort",
       "merge": "Mergesort",
-      "heap" : "Heap Sort"
+      "heap" : "Heap Sort",
+      "radixlsd" : "Radix LSD sort"
     }
   },
   "string": {
diff --git a/algorithm/sorting/radixlsd/basic/code.js b/algorithm/sorting/radixlsd/basic/code.js
new file mode 100644
index 00000000..1dc8aba9
--- /dev/null
+++ b/algorithm/sorting/radixlsd/basic/code.js
@@ -0,0 +1,44 @@
+tracer._print('original array = [' + D[0].join(', ') + ']');
+tracer._sleep(1000);
+tracer._pace(300);
+function pow(base, expo){
+	var ans = 1;
+	for(var i = 0; i < expo;i++){
+		ans *= base;
+	}
+	return ans;
+}
+for(var exp = 0; exp < 6;exp ++){
+	tracer._print("Bit "+exp);
+	for(var i = 0; i < D[0].length; i++){
+		tracer._select(0, i);
+		D[2][ parseInt( D[0][i] / pow(10, exp)  % 10) ] += 1;
+		tracer._notify(2, parseInt( D[0][i] / pow(10, exp)  % 10) );
+		tracer._deselect(0, i);
+	}
+	for(var i = 1; i < 10; i++){
+		tracer._select(2, i - 1);
+		D[2][i] += D[2][i - 1];
+		tracer._notify(2, i);
+		tracer._deselect(2, i - 1);
+	}
+	for(var i = D[0].length - 1; i >= 0; i--){
+		tracer._select(0, i);
+		D[2][parseInt( D[0][i] / pow(10, exp)  % 10) ] -= 1;
+		tracer._notify(2, parseInt( D[0][i] / pow(10, exp)  % 10) );
+		D[1][ D[2][ parseInt( D[0][i] / pow(10, exp)  % 10) ] ] = D[0][i];
+		tracer._notify(1, D[2][ parseInt( D[0][i] / pow(10, exp)  % 10) ] );
+		tracer._deselect(0, i);
+	}
+	for(var i = 0; i < D[0].length; i++){
+		tracer._select(1, i);
+		D[0][i] = D[1][i];
+		tracer._notify(0, i);
+		tracer._deselect(1, i);
+	}
+	for(var i = 0; i < 10; i++){
+		D[2][i] = 0;
+		tracer._notify(2, i);
+	}	
+}
+tracer._print('sorted array = [' + D[0].join(', ') + ']');
diff --git a/algorithm/sorting/radixlsd/basic/data.js b/algorithm/sorting/radixlsd/basic/data.js
new file mode 100644
index 00000000..26e69e58
--- /dev/null
+++ b/algorithm/sorting/radixlsd/basic/data.js
@@ -0,0 +1,8 @@
+var tracer = new Array2DTracer();
+var k = [5,4,3,5,7,5,6,9];
+var D = [
+	k,
+	Array1D.random(k.length),
+	[0,0,0,0,0,0,0,0,0,0]
+];
+tracer._setData(D);
diff --git a/algorithm/sorting/radixlsd/desc.json b/algorithm/sorting/radixlsd/desc.json
new file mode 100644
index 00000000..2e2bb9c7
--- /dev/null
+++ b/algorithm/sorting/radixlsd/desc.json
@@ -0,0 +1,13 @@
+{
+  "Radix LSD Sort": "Radix sort is a non-comparative integer sorting algorithm that sorts data with integer keys by grouping keys by the individual digits which share the same significant position and value.",
+  "Complexity": {
+    "time": "worst O(n), best O(n), average O(n)",
+    "space": "always O(n)"
+  },
+  "References": [
+    "<a href='https://en.wikipedia.org/wiki/Radix_sort'>Wikipedia</a>"
+  ],
+  "files": {
+    "basic": "Basic"
+  }
+}
diff --git a/algorithm/sorting/selection/basic/code.js b/algorithm/sorting/selection/basic/code.js
index efeefe59..f82b88e8 100644
--- a/algorithm/sorting/selection/basic/code.js
+++ b/algorithm/sorting/selection/basic/code.js
@@ -5,11 +5,12 @@ for (var i = 0; i < D.length - 1; i++) {
     var minJ = i;
     tracer._select(i);
     for (var j = i + 1; j < D.length; j++) {
+    	tracer._select(j);
         if (D[j] < D[minJ]) {
-            tracer._select(j);
+            tracer._notify(j);
             minJ = j;
-            tracer._deselect(j);
         }
+        tracer._deselect(j);
     }
     if (minJ != i) {
         tracer._print('swap ' + D[i] + ' and ' + D[minJ]);
@@ -20,4 +21,4 @@ for (var i = 0; i < D.length - 1; i++) {
     }
     tracer._deselect(i);
 }
-tracer._print('sorted array = [' + D.join(', ') + ']');
\ No newline at end of file
+tracer._print('sorted array = [' + D.join(', ') + ']');