Abstract: In order to achieve perforation and formation testing at in multiple layers,or to do perforation and formation testing at in the same layer twice in one trip run,a string combining layered perforation and formation testing functions has been developed.Its core idea is to add a pressure relief device,two levels of shock absorbing device to the conventional perforation string,and to change the secondary initiation method from conventional mechanical ignition to electric initiation.In addition,the combined operation mode with perforating string connected inseries and APR full size tester was adopted.The pressure relief device and shock absorbing device in perforating string has solved the problem perforation at the exit of detonation pressure and strong vibration impact to secondary blasting gun string device and electric initiationg ensures blast reliabilitying.The application of the combined string in 3 wells was successful,with perforating emission rate of 100%,and testing results were consistent with well logging interpretation,then reservoir was brought into production.The application showed this technology with simplified downhole tools and wellhead unit,could make field operation easier,and lower the cost of downhole operation and perforation by 27%;enhance the accuracy of layered formation test and shorten the testing cycle,and improve success rate of formation testing by 37%.