The invention provides a full-automatic four-wire testing machine for a circuit board. The testing machine comprises a feeding unit, a testing unit, and a discharging unit. The feeding unit transmits a circuit board from a placing position to a testing position. The testing unit adjusts a pin plate of a testing tool automatically by using a fine tuning device, thereby testing the circuit board precisely. The discharging unit conveys the circuit board after testing completion to a corresponding area according to a testing execution situation. According to the testing machine, the feeding unit can convey laminated circuit boards; the testing unit can carry out alignment fine tuning on the circuit board that does not pass the test and then test the circuit board; and the discharging unit conveys the circuit board after test completion to the corresponding area based on the testing result. High-efficiency inputting and classified outputting as well as accurate alignment and testing are realized. Therefore, the testing efficiency and yield of the circuit boards are improved; the cost is lowered; and resource wasting is reduced.