The present invention provides a self-priming experimental instrument and a detection method, and belongs to the technical field of experiments. An inner chamber base plate of a box body is connected to movable adjusting lever; the movable adjusting lever is connected to a slider; the slider is connected to a fixed platform; the fixed platform is connected to an object weighing basket; a rotary knob is connected to the slider and movable adjusting lever; the slider moves or is fixed to the adjusting lever through the rotary knob; the front of the box body is connected to a left glass sash window and a right glass sash window; a balance is placed on the box top; the balance is connected to the basket; and the balance is connected to the computer by a cable. The method has the advantages of easy operation in the experimental research, reduction of the error caused by personnel, machinery intervention and improvement of work efficiency, simple operation, less manual intervention, capability of unattended continuous automatic test, visual interface, visual acquisition of data and simple data processing.