In order to acquire synchronous multi-information in precision agriculture, a mobile soil moisture instrument with GPS position function was developed. This device, which mainly consists of a single-chip microcomputer (SCM), a keyboard, a Liquid Crystal Display (LCD), several sensors and a GPS receiver, was designed to synchronously integrate the signals from both sensors and GPS receiver. In this paper, results showed it worked very well with a Standing Wave Ratio (SWR-2) sensor and GPS25 receiver in respectively obtaining high-precise multiple soil moisture information of vegetable terra, cropland and gravel terra. In addition, the following plane and section tests using the instrument and its corresponding interpolation analysis with software Arcview also afforded a feasible and effective method for further soil moisture researches.