For this reason,period check is neccessory for ensuring the accuracy and precision of this method.

The theoretical principle,procedure and methodologies of the period check in measurement practices are introduced.

Based on the laboratory work,the necessity to test intermediate checks of laboratory is elaborated,and the common check methods are narrated.

This paper introduces the work of intermediate checks by Accreditation Criteria for laboratories , Take the intermediate check for CG5001 calibration generator for example,the concrete work process of intermediate checks is introduced.

This paper expounds the significance of the intermediate checks of the measurement standard, introduces the principles of the control chart and the objects of the intermediate checks, and puts forward the method for carrying out the intermediate checks on second-class piston manometer by using the Control Chart(GB/T4091-2001).

Instruments intermediate check is an important aspect in laboratory certification and the check is one of quality management mode of national laboratory certification and measurement accreditation requirement.

Through explaining the definition and importance of intermediate check for device and equipment,this paper expounds the application of intermediate check in water quality analysis laboratory.

The article stresses the necessity of intermediate check to civil engineering lab and then introduces the way of doing the check work well.