diff --git a/flash-tool/cmd.c b/flash-tool/cmd.c
index ee10735..2772a60 100644
--- a/flash-tool/cmd.c
+++ b/flash-tool/cmd.c
@@ -40,7 +40,7 @@ extern char com_argv[MAX_ARGC][MAX_COMMAND_LENGTH];
 struct ingenic_dev ingenic_dev;
 struct hand hand;
 
-static struct nand_in nand_in;
+struct nand_in nand_in;
 static struct nand_out nand_out;
 unsigned int total_size;
 unsigned char code_buf[4 * 512 * 1024];
@@ -544,6 +544,8 @@ int init_nand_in(void)
 	nand_in.check = error_check;
 	nand_in.dev = 0;
 	nand_in.cs_map = cs;
+	memset(nand_in.cs_map, 0, MAX_DEV_NUM);
+
 	nand_in.max_chip = 16;
 	return 0;
 }
@@ -561,7 +563,6 @@ int nand_prog(void)
 		"\n \t-n:\tno oob"
 		"\n \t-o:\twith oob no ecc"
 		"\n \t-e:\twith oob and ecc";
-	init_nand_in();
 
 	if (com_argc != 6) {
 		printf("\n not enough argument.");
@@ -569,8 +570,7 @@ int nand_prog(void)
 		return 0;
 	}
 
-	for (i = 0; i < MAX_DEV_NUM; i++)
-		(nand_in.cs_map)[i] = 0;
+	init_nand_in();
 
 	nand_in.start = atoi(com_argv[1]);
 	image_file = com_argv[2];
@@ -613,9 +613,6 @@ int nand_query(void)
 	}
 	init_nand_in();
 
-	for (i = 0; i < MAX_DEV_NUM; i++)
-		(nand_in.cs_map)[i] = 0;
-
 	nand_in.dev = atoi(com_argv[1]);
 	(nand_in.cs_map)[atoi(com_argv[2])] = 1;
 
diff --git a/flash-tool/cmd.h b/flash-tool/cmd.h
index 6e8fcc2..57d7fa4 100644
--- a/flash-tool/cmd.h
+++ b/flash-tool/cmd.h
@@ -22,6 +22,8 @@
 #ifndef __CMD_H__
 #define __CMD_H__
 
+#include "usb_boot_defines.h"
+
 #define COMMAND_NUM 31
 #define MAX_ARGC	10
 #define MAX_COMMAND_LENGTH	100
@@ -29,5 +31,6 @@
 int boot(char *stage1_path, char *stage2_path);
 int nand_prog(void);
 int nand_query(void);
+int nand_erase(struct nand_in *nand_in);
 
 #endif  /* __CMD_H__ */
diff --git a/flash-tool/command_line.c b/flash-tool/command_line.c
index bc09093..922b013 100644
--- a/flash-tool/command_line.c
+++ b/flash-tool/command_line.c
@@ -27,6 +27,7 @@
 #include "cmd.h"
 #include "config.h"
  
+extern struct nand_in nand_in;
 int com_argc;
 char com_argv[MAX_ARGC][MAX_COMMAND_LENGTH];
 
@@ -42,7 +43,7 @@ static const char COMMAND[][30]=
 	"nerase",
 	"nread",
 	"nreadraw",
-	"nreadoob",
+	"nreadoob", /* index 10 */
 	"nprog",
 	"help",
 	"version",
@@ -52,7 +53,7 @@ static const char COMMAND[][30]=
 	"readnand",
 	"gpios",
 	"gpioc",
-	"boot",
+	"boot", /* index 20 */
 	"list",
 	"select",
 	"unselect",
@@ -110,6 +111,37 @@ static int handle_fconfig(void)
 	return 1;
 }
 
+/* need transfer two para :blk_num ,start_blk */
+int handle_nerase(void)
+{
+	int i;
+	if (com_argc < 5) {
+		printf("\n Usage:");
+		printf(" nerase (1) (2) (3) (4) ");
+		printf("\n 1:start block number"
+		       "\n 2:block length"
+		       "\n 3:device index number"
+		       "\n 4:flash chip index number");
+		return -1;
+	}
+
+	init_nand_in();
+
+	nand_in.start = atoi(com_argv[1]);
+	nand_in.length = atoi(com_argv[2]);
+	nand_in.dev = atoi(com_argv[3]);
+	if (atoi(com_argv[4]) >= MAX_DEV_NUM) {
+		printf("\n Flash index number overflow!");
+		return -1;
+	}
+	(nand_in.cs_map)[atoi(com_argv[4])] = 1;
+
+	if (nand_erase(&nand_in) < 1)
+		return -1;
+
+	return 1;
+}
+
 int command_interpret(char * com_buf)
 {
 	char *buf = com_buf;
@@ -158,6 +190,9 @@ int command_handle(char *buf)
 	case 6:
 		nand_query();
 		break;
+	case 7:	
+		handle_nerase();
+		break;
 	case 11:
 		nand_prog();
 		break;