Abstract: According to the principle of hydraulic fracturing and active carbon radon measuring method, we try to apply active carbon radon measuring method to monitor cracks in coal rock by hydraulic fracturing. Four experiments were carried out in Changzhi city of Shanxi province. By comparing the radon value before and after fracturing within three years, we found that radon appeared obvious anomaly on the ground after fracturing. With the passage of time, the range of radon anomaly gradually decreases and tends to disappear. The results show that the method of active carbon measuring radon can respond to the disturbance caused by hydraulic fracturing of coal and rock.