Slope monitoring is a critical step to ensure the safety of excavation. However, conventional manual method using inclinometer is unable to fulfill realtime data acquisition and automated management because of its inefficiency and low monitoring frequency. So we use Internet of Things technology to develop a remote and automatic slope monitoring system based on electronic dip angle sensor. This paper presents the operating principle，constitution of this system and tests of its performance. According to the results, resolution, long term error and applicable accuracy of the sensor are 0.000002 rad, 0.0002 rad, and 0.0001 rad respectively. In the laboratory, the system has water repellency under the water pressure of 100 m and relative tolerance of 0.12 mm/m, which tentatively satisfies remote automation of excavation monitoring.