The invention relates to detecting method and system applied to information interaction of an intelligent assembly. The method comprises the following steps: (1) simulating and outputting a sensor signal to a sensor through an online monitoring testing instrument; (2) sending acquiring information to a state monitoring IED through the sensor; (3) uploading the information to a monitoring background through the state monitoring IED; (4) simulating and outputting a signal to an online monitoring testing product through the online monitoring testing instrument; (5) uploading the information to the monitoring background through the online monitoring testing product; (6) comparing and analyzing the uploaded information through the monitoring background to obtain the detecting result. The system comprises the online monitoring testing instrument, the sensor, the state monitoring IED and the monitoring background which are sequentially connected. With the adoption of the method and system, the labor cost and material cost in information interaction detection of the intelligent assembly can be saved; the information interaction functions are enriched; a user can conveniently monitor the operation information of each device at the monitoring site.