Developing from IC and PCB, the SIP (system in a package) has already been one of the most important development directions of future electronic system; therefore, we desiderate the study of testing design and test method. Being incapable of adding circuits for testable design, the SIP can only design test method and process according to the existing resources. Test method in this paper takes into account both the IC characteristic and the PCB characteristic of SIP, using the test results of bare dies and substrates in SIP, combined with the SIP production process, identify the steps may cause failure, determine the test projects, and finally complete the test method design. At the same time, consideration has already be given to both test coverage and the cost, it fulfill the actual requirement of SIP.