The environmental dust content of the ammonia escape monitoring of the power plant is quite large, which is determined by the location of the monitoring point. Most of the ammonia escape monitoring points are located before the dust collector. The dust content reaches several thousand milligrams per cubic meter, or even dozens of grams per cubic meter. Ammonia escape monitoring needs to have a relatively fast response speed, so that the amount of ammonia injected can be controlled in a relatively short time through the monitoring and feedback of ammonia escape. The extraction pretreatment type delays the response time, and in such a high dust environment, the extraction type will bring a large amount of maintenance in the later stage. Therefore, a better monitoring option is to directly install and detect online laser spectroscopy. A power plant in Guangdong used several sets of laser spectroscopy online analysis systems of Canada unisearch in the monitoring of ammonia escape from denitrification, realizing online direct detection.