With the rapid development of society today, people’s demands for living environments are continuously rising. Considering users’ needs for indoor environments and safety concerns, we have developed an indoor environment monitoring system based on STM32. This system uses temperature and humidity sensors, smoke sensors, light sensors, air quality sensors, and human body infrared sensors to monitor various indoor environmental parameters. The data is displayed in real-time on a mobile APP. Additionally, by using the WIFI module ESP8266-01S, the monitoring results are uploaded to a cloud platform, allowing users to remotely view relevant parameters through the mobile APP. The system sets safety thresholds for the smoke sensor and air quality sensor; if these thresholds are exceeded, the system will trigger a light warning. If the light level drops below the threshold or if the human body infrared sensor detects a person, the system will also trigger a light warning. This system aims to overcome the limitations of on-site monitoring in terms of time and space, optimize living environments, enhance the quality of living environments, reduce power consumption, and increase user safety.