The invention discloses a flow chamber of a flow cytometer, and relates to the field of flow cytometers. By adopting the flow chamber, the problems that when the sample feeding rate of a sample flow of an existing flow cytometer is increased, to-be-tested cells or micro-particles are deviated from the central position of an irradiation light spot to cause that the irradiation energy is non-uniform, signal changes are increased, and data quality is reduced, and thus the detection precision of the cytometer is reduced can be solved. The flow chamber comprises an inlet area, a converging area, an adjusting area, a detection area and an auxiliary area, wherein the inlet area is provided with a main sheath liquid inlet, a sample flow inlet and an air pressure adjusting opening, the adjusting area is provided with two adjusting area inlets and a comprehensive adjusting area, main sheath liquid enters the inlet area from the sheath liquid inlet, the sample flow enters the converging area from a sample flow pipe, and the main sheath liquid and the sample flow are converged into a steady laminar flow in the converging area by using hydrodynamic focusing characteristics and then sequentially enter the comprehensive adjusting area, the detection area and the auxiliary area. According to the flow chamber disclosed by the invention, relatively high detection precision can be achieved at both high and low sample flow sample feeding rates, particularly, the nuclear flow diameter obtained after the sample flow is converged can be reduced at a high sample flow sample feeding rate, and high precision can be achieved.