A crossbow is provided with a silent crank-cocking device including a shaft extending through a positioning sleeve, reels, a housing, a bushing, covers, a shaft sleeve, limiting pieces and a clutch wrench. A crank is connected to an end of the shaft. The reels are connected to two ends of the shaft. The housing receives the bushing, which includes a hole and clutch slots. The covers are connected to both ends of the housing. Rollers are located in the clutch slots. The limiting pieces are arranged on two ends of the shaft sleeve. The clutch wrench includes a portion connected to the rollers in the housing and another portion extending from the housing.