Abstract: The specific impact of residual stresses in aluminum-alloy engine cylinder head on crack forming was an-alyzed,while adopting the blind-hole method to measure the level and distribution of the residual stresses in thecracking areas and some other sensitive parts of three groups. Considering cylinder head's complex structure andthe position of the measuring points,the processes of drilling blind holes and milling the pipelines and their sideplates were conducted by a milling and drilling machine in this study. The time-domain curves of strain at themeasuring points were recorded by a 30-channel strain gauge (DRA-30A) during stress releasing in the processesof drilling and milling. The test results showed that the primary cause of cracks in the cylinder head is,that the re-sidual stresses in the pipelines is mainly compressive stress but in the top surface of the lower part it is tensilestress. The highest possible area of forming crack is in Point 4, and the most obvious tensile effect on the lower partresulted from the pipeline in Point 7. The structure design and processing technology of Group B90 are the mostreasonable in all three groups. According to the test results and research conclusion,the new cylinder head canmeet the design requirements after improving the structure and processing technology.