A real-time monitoring instrument for colluvial landslides that can capture horizontal displacement during the deformation period of the slope, deep dislocation displacement, accurate depth of the slip surface, and sliding direction during the initial sliding period has been developed. The horizontal displacement monitoring system is a monitoring apparatus assembled in an array based on the MEMS (Micro-Electro-Mechanical System). Horizontal displacement is obtained by integration of the X- and Y-direction angles along the drilling direction, and the sliding direction is simultaneously measured via vector composition of the X- and Y-direction angles obtained from the MEMS sensor. Deep dislocation displacement is calculated based on the relative displacement between the base point embedded in the bedrock and measuring point above the sliding surface, and measurement of relative displacement is executed by an angular displacement sensor fixed on top of the inclinometer tube. The accurate depth measurement of the slip surface is transferred to the judgment about the on-off state of the signal wire. Based on the long-term monitoring of the Yu Jiaba landslide at the Three George dams, an open-pit mine in Inner Mongolia province, and an Anshan open-pit mine, the results reveal that the reliability of the instrument is very high. High accuracy, ability to capture the entire landslide process, large deformation monitoring, autonomous data collection, and reusable characteristics could be implemented.