A horizontal drilling machine with an in-situ detection device, including a support frame, an armored cable, a steel pipe-straightening mechanism, a steel pipe-feeding mechanism, a motor, a power head, a drill pipe, a rotating chuck, a damper, a non-core drilling tool, the in-situ detection device, a fishing device and a thrust cylinder. The steel pipe-straightening mechanism, the steel pipe-feeding mechanism, the rotating chuck and the damper are sequentially fixed on the support frame from left to right. One end of the thrust cylinder is hinged with the support frame, and the other end is connected to the power head. The active drill pipe of the power head is connected to the drill pipe. An end of the armored cable is connected to the fishing device in the drill pipe, and the fishing head of the fishing device is connected to the spearhead of the non-core drilling tool.