Some different ways to express the environment conditions are summarized, including the natural environment, artificial environment, physical environment, chemical environment etc. Four elements of metrology and calibration environment, namely the environment medium, environment field, environment mechanics conditions, and environment space are presented out to standardize and construct a complex environment. The main environmental element classification method is proposed, and the subsequent elements are listed in descending according to their importance in describing the complex and changing environmental conditions. The strategy to the complex environment influences in metrology and calibration are summarized, including the technique upgrade, local environment control, and environmental factor dimension reduction etc.