Abstract: Currently,applications based on location technology have become one of the most development potential Internet of Things(IOT) business．Because IOT sensing layer sensor nodes are limited by their own power consumption and processing capability,they can not directly solve the equation of wireless positioning algorithm．This paper modified traditional trilateral positioning algorithm by the method of geometric approximate calculation．New algorithm process only needs to make simple comparison,addition,subtraction,multiplication,and division operations to get location information of the node．It introduces a certain error value in the solving process,but significantly reduces solving complexity and providing a feasible solution for the low operational capability processor to directly calculate positioning information．Positioning experiment evaluation shows that the positioning average error of the algorithm is 1.18m,and it can satisfy the most small and medium-sized scene range positioning requirements.

Key words: Internet of things,Trilateral positioning algorithm,Positioning error,Microcontroller