The invention discloses an object density detection method based on an intelligent robot system and belongs to the technical field of intelligent robots. A main manipulator of a main robot unit grabsa to-be-detected object on an objective table and places the to-be-detected object on a weighing mechanism of a density detection unit for weighing, the mass of the to-be-detected object is m(object),the to-be-detected object is soaked in to a measuring solution tank of the density detection unit, the mass change of the weighing mechanism is measured to be delta m, the density of the to-be-detected object is calculated in the description, wherein Rho(solution) is the density of a solution. The to-be-detected object is firstly put on the weighing mechanism to be weighed and then soaked in thesolution to be weighed, and the density of the to-be-detected object is further detected; particularly, when the method is used for density detection of dangerous chemicals, influences of the dangerous chemicals on human body health can be effectively avoided.