Abstract: In order to improve testing precision of contact resistance of high-voltage switch,the paper proposed a method which used pulse power supply mode to measure contact resistance of high-voltage switch.It analyzed measurement principle of the contact resistance of high-voltage switch,introduced hardware and software design of the contact resistance testing instrument of high-voltage switch which took embedded LPC2378 processor as core in details.The actual application showed that the testing instrument has many advantages such as high precision,good stabilization,easy to carrying.