In this paper, we have employed non-linear model reexamine real interest parity (RIP) of five European economies with respect to the US. We focus on using linear and nonlinear unit root tests to test real interest rate differentials (RIRD). And we add time trend in the logistic and exponential smooth transition regression models to monthly data. The results are as follows. First, the evidence for the full-sample is favorable using three traditional unit root tests and one powerful nonlinear unit root test. Almost all economics are support real interest parity. Second, we use nonlinear error correction model to find which factors influence on RIRD. There are three economics influenced by both domestic and foreign factors at the same time.