Abstract：CSD–60 sliding micrometer is developed in three stages，and precision sensor and INVAR steel are adopted in the device development. The CSD–60 sliding micrometer is developed from gauging distance and contraction style based on overseas products. Three invention patents are authorized；and the new products such as three-petal sliding micrometer are presented. Data acquisition instrument is considered corresponding to the products for improving the efficiency of in-situ tests；and related software is developed for data processing；so the firsthand monitoring information can be achieved. Long-term experiments on calibration and linearity assembly are performed for the serial products. Statistical analysis of the experimental data shows that observation theory and structure of instrument are greatly improved in the third stage；three-petal contact is prior to four-petal one in geometric stability. The precision of CSD–60 sliding micrometer is 0.02 mm/m with working temperature ranging from –10 ℃ to 50 ℃. Its water resistance is over 0.5 MPa，which can meet the requirements of civil engineering. If high accuracy sensor is applied to CSD–60 sliding micrometer or three-petal contact method is substituted for four-petal one，the gauging precision of CSD–60 sliding micrometer will be further improved.
