The invention provides a portable subway vehicle weighing device which includes a screw adjusting unit, support platforms, and sensors. The two ends of the screw adjusting unit are fixedly connected with the two support platforms. The screw adjusting unit can drive the support platforms to move to the two ends or to the middle. The sensors are fixedly arranged inside the support platforms. The beneficial effects are as follows: the portable subway vehicle weighing device is simple, small and light; the position of the device can be adjusted at any time in a simpler and more labor-saving manner, and thus, the device can adapt to various subway vehicles with different wheel bases and lengths between truck centers; and a single wheel is weighed using multiple sensors, and the weighing range and weighing efficiency of the weighing device are improved.