Provided is a strong and weak electricity switching and testing circuit which comprises resistors R1-R4, a relay K203, a relay K204, pull-down resistors R5-R8, pull-up resistors R9-R12, a Schmitt trigger and a driver. The relay K203 and the relay K204 are four-contact relays. Defects in the prior art are overcome, and a strong and weak electricity switching and safety mechanism analog circuit is provided so that detection of strong electricity functions, such as testing, safety protection removing, detonating, etc., of missile board system initiating explosive devices is ensured to be completed under the situation of unchanging the testing state via the strong and weak electricity switching and testing circuit before abutting joints of plugs of the initiating explosive devices so that testing process is simplified and testing efficiency is enhanced.