Method and deice for measuring equal yield density while drilling

The invention discloses a method and a device for measuring equal yield density while drilling. Annular pressure is measured while drilling, drilling depth and a well track are traced automatically in a downhole, the equal yield density of a drilling fluid and the change of the equal yield density are monitored in real time, whether the equal yield density is in an allowable safe window range is judged, conditions such as downhole pressure control, well cleaning, formation fluid immersion and the like can be mastered timely, a drilling technician can be effectively guided for construction, downhole troublesome conditions and accidents are prevented, drilling to a target layer is realized safely and smoothly, and expected drilling purposes such as reservoir protection and the like are achieved.