With the improvement of the degree of aging, the traditional pension model can no longer meet the growing needs of the elderly. Therefore, it is necessary to use the intelligent means of information technology to improve the level of pension services. This paper will integrate multi-sensor fusion technology, NB-IoT communication technology and cloud platform technology to develop and design a smart pension online monitoring system to realize real-time collection of human health and motion status information and realize monitoring platform management. In this system, STM32 microcontroller will be used as the main control module, and MAX30102, ADXL345 and DS18B20 sensors will be used to collect the heart rate, blood oxygen, displacement and body temperature of the human body in real time. On the one hand, the communication part is completed by the BC20 Internet of Things module. The data transmission between the terminal detection device and the cloud platform, on the other hand, the HC-42 Bluetooth module is used to complete the data communication with the mobile phone. The test results show that the system can collect and process data accurately in real time and maintain good communication with the cloud platform and mobile phone. The designed system has strong pertinence, easy operation, high reliability and broad development prospects.