The invention relates to a comprehensive tester for loop resistance testing and mechanical characteristic testing of a circuit breaker. The comprehensive tester is characterized by that a 220-kV inputvoltage, an adjustable resistor R1, an adjustable resistor R2, a switch K2, a rectifier and a first node are connected successively. A loop resistance calculation circuit is provided with two nodes for connection between a synchronous-opening synchronous-closing switch K3 and a synchronous-opening synchronous-closing switch K3'and is provided with two voltage connection points U and U' for connection with a tested circuit breaker. Two nodes are arranged at a mechanical characteristic calculation circuit; a three-position switch K4 is arranged between one node and a first node; a three-position switch K4'is arranged between the node and a ground terminal of a switch K1; and the current flowing through the three-station switches K4'and K4 are connected with the tested circuit breaker. On the basis of the reasonable design, the loop resistance testing and mechanical characteristic testing are carried out simultaneously; the complicated operation caused by inconvenience of testing wire replacement of the two kinds of tests is eliminated; the testing difficulty is reduced; and the test efficiency is improved effectively.