Underground detection device for leakage of petroleum drilling fluid

The utility model provides an underground detection device for leakage of petroleum drilling fluid, which relates to the technical field of well drilling and comprises a drill collar, an external measuring device, an internal measuring device and a measuring circuit board. A flow measuring short section is arranged in the drill collar, the drill collar is connected with the flow measuring short section through an anchor bolt, and an annulus is formed between the drill collar and the flow measuring short section. The measuring circuit board is arranged in the flow measuring short section, and the external measuring device and the internal measuring device are both electrically connected with the measuring circuit board. According to the utility model, the increase and loss of the drilling fluid in a shaft are found in time by comparing the difference of the flow of the drilling fluid inside and outside the drill collar, and the measurement result is directly obtained underground and is transmitted to the groun