<p>Helical flute are the core geometric structures of tools such as end mills, drills, taps and so on, significantly influencing their cutting performance. Among these, the conical helical flute has become the focus of attention due to its excellent chip curling and removal capabilities, as well as high rigidity and vibration resistance. However, the profile of the conical helical flute exhibits continuous variation along the tool axis, which not only complicates the precise description of the flute surface but also poses challenges to accurate grinding, particularly when multiple constraints are imposed. To address this issue, a novel wheel method for grinding conical helical flute with constraints on the constant rake angle, helix angle, flute width and taper angle of core radius is proposed. This method accurately calculates the grinding trajectory of standard grinding wheel based on the surface conjugation theory and envelope theory. Firstly, a parametric model is developed to characterize the constant helix angle of the conical helical flute edge, with the parameters of the flute profile explicitly defined and mathematically expressed. Then, a parametric model is established to describe the rotation profile of grinding wheel, and a kinematic model is formulated to represent the relative motion between the grinding wheel and the conical helical flute. In addition, a geometric mapping relationship model is constructed to correlate the constraints of constant rake angle and helix angle with the grinding wheel trajectory. Based on the model, constraint relationship models are further developed to link the taper angle of core radius and flute width with the grinding wheel position, incorporating the constraints imposed by the specified core radius on the reference cross-section and the constant taper angle. Finally, the particle swarm optimization (PSO) algorithm is applied to perform multi-objective optimization, determining the optimal grinding orientation and position of the wheel. Through a series of simulation and actual grinding experiments, supplemented by precise measurements, the effectiveness and accuracy of the proposed grinding trajectory method are rigorously validated. The experimental results demonstrate that the rake angle, helix angle, flute width and taper angle of core radius are accurate and constant, with the maximum relative errors below 0.5%. Furthermore, the method with good adaptability could be extended to other grinding processes.</p>