For the small and medium power diesel engine, the cylinder head of the multi cylinder machine is to cast all the cylinder heads together to become a unified multi cylinder cylinder head, which is compact and small. The cylinder head is the most complex structure of the diesel engine. Its main function is to seal the cylinder and form a combustion chamber with the top of the piston and the cylinder wall. The inspection and disassembly of cylinder head assembly and cylinder head crack of diesel engine are described below for reference of diesel engine maintenance personnel and agricultural vehicle drivers.