The structural performance and reliability can be affected by the strength degradation and significant repetitive load events whose occurrence rate may be different in different environments. Furthermore, in the case of the environment affecting load and strength simultaneously, the correlation analysis between load and strength should be considered. Therefore, this paper deals with the time-dependent reliability modelling problem based on the load-strength model, which incorporates the actual environmental effects into the reliability estimation in two ways: 1) the occurrence rate of the load affected by the actual environment; 2) the variable correlation between load and strength. A numerical example is given to illustrate the necessity of the environmental analysis for the time-dependent reliability modelling¹.