With the rapid development of mobile internet and pervasion of Location-Based Service (LBS), location privacy has become an important issue. In this paper, we present DeCache, a modified location privacy protection system model, which pre-caches the user-demanded LBS data. So the mobile users don't have to send the network LBS requests when they need to access LBS. This is more secure than the previous system model with intermediate server. To realize the model, we make the following contributions: 1) adding a mobile location middleware in the mobile operating system to compute users' mobility pattern; 2) proposing a two-level cache to get the LBS data in advance. To demonstrate the effectiveness of our strategy, we carry out extensive simulations and the results show that DeCache can solve the location privacy problem without compromising the accuracy.