With the rapid economic development of China, the pile foundation method has been widely employed thanks to its unique merits. To guarantee the accuracy of the designing parameters, it is very important to analyze and investigate the distribution state of strain and stress. This paper deals mainly with the principle and procedures of the sliding micrometric linear technology for monitoring strain (internal force) of the pile body. A practical engineering example is given to illustrate the effectiveness of the linear technology for monitoring strain in static load pile test.