@ha_chaeyeon, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project 
See About the Installation & Troubleshooting category.
Although I don't know too much about BleuTooth modules, please post the sketch (and use code tags). Are you using SoftwareSerial (on which pins)? Or hardware serial on pins 0 and 1?