The invention discloses a synchronous acquisition circuit of electric car lithium ion power battery pack voltage and a control method of the synchronous acquisition circuit. According to the circuit, a low-cost low power consumption single-chip microcomputer is adopted as a simulation sampling front end, a battery monomer is used for directly supplying power for the single-chip microcomputer, voltage converting is not required, power supplied by an isolated power source is not needed, the structure is simple, and the cost is low; by the configuration of a resistor, the ID configuration of the simulation sampling front end is realized, and volume production is easy; an optocoupler is adopted to achieve the isolated transmission of trigger pulse, and the synchronous precision is high; a unidirectional isolated asynchronization serial data bus and a time division multiple access data transmission mechanism are adopted, each battery monomer only needs one optocoupler to realize the data transmission between the simulation sampling front end and a master controller, the bus structure is simple, and the data transmission efficiency is high.