The invention relates to a building indoor environmental monitoring system and method. The indoor environmental monitoring system combined with building environment simulation is formed by an environment monitoring system, a building environment simulation system, a server and a terminal. The indoor environmental monitoring method combined with building environment simulation includes the steps: utilizing the environment monitoring system and the building environment simulation system to simulate the current building indoor environmental parameter distribution result calculated in the server; and combining with the actual measurement value of the environmental monitoring system, calibrating and correcting the simulation result so as to output a relatively more accurate corrected indoor environmental parameter distribution result in the terminal. The indoor environmental monitoring system and method combined with building environment simulation can realize accurate monitoring of indoor environmental parameter distribution in a low density sensing network, based on reduction of the number of sensors, so as to improve the present situation of building information asymmetry and use the distributed environmental parameters to replace the single parameter. And at the same time, with combination of personnel distribution and the above distributed environment parameters, the indoor environmental monitoring system and method combined with building environment simulation can be targeted to design the control strategy so as to improve the environmental quality and personnel satisfaction degree, and can realize energy conservation at the same time.