In this study, we use the generalized integration constants method “GCI” [1,2] to quantize two fields with constraints. Indeed, Proca field, that describes a massive boson is studied first, based on a Lagrangian without gauge symmetry, in order to determine the necessary brackets for its canonical quantization. Then, another gauge invariant version of this field, obtained by adding an additional scalar field in the mass term, is quantized after fixing this gauge.”