The combined vacuum nickel-based brazing and heat treatment process is proposed for the deformation of Coriolis mass flowmeter measuring tubes and residual internal stresses caused by the traditional silver-based manual brazing process. The process optimizes the welding process of the flowmeter, reduces the generation of internal stresses, and improves the symmetry of the vibration system through the steps of precision positioning and calibration, surface plasma treatment, gradient brazing material laying, and vacuum brazing, etc.To further eliminate internal stresses, the annealing and insulation process is used, which significantly improved the mechanical properties and measurement stability of the flowmeter. The test results show that the improved process enables the flowmeter to have an average error within 0.14% and a repeatability of up to 0.07%, which meets the requirements of class 0.15 accuracy. This research not only significantly improves the measurement performance of Coriolis mass flowmeter, but also provides an effective stress control method for the manufacture of vibration type precision sensors, which has important engineering application value and promotion prospects.