The invention discloses a wide-area measurement system (WAMS) phasor measurement unit (PMU) optimization configuration method taking an information security constraint into consideration. Through reasonable optimization configuration of PMU equipment in a WAMS, under the condition that system observability is guaranteed, in case of information attack, calculation result deviations of state estimation can be limited within a set threshold. According to the method, when system security is considered, in case of the possibility that attackers may consider lunching information tempering attacks at power system network vulnerable nodes or nodes most severely affected by the attacks, it is ensured that the state estimation deviations of the system can also be controlled within a preset acceptable scope even if the system faces the most extreme information tampering attack site selection. The method provided by the invention, under the condition that the system observability is guaranteed, can reduce the state estimation deviations when the system encounters similar malicious information tampering attacks, enables the deviations to be controlled within the preset acceptable scope and realizes the purpose of maintaining security of a power information physical system.