Disclosed are a CMOS image sensor pixel structure and a manufacturing method thereof. The structure comprises a light sensitive element (37) arranged on a silicon substrate (31), and a multi-layer structure used for a standard CMOS device. A deep groove (38) provided with a light-transmitting space is formed above the light sensitive element, a side wall of the deep groove is surrounded by light reflection shielding layers (39), and the light reflection shielding layers are continuously arranged in a longitudinal direction, so as to reflect incident light on the light reflection shielding layers. According to the present invention, the deep groove is surrounded by annular metal interconnecting wires, through holes, contact holes, and polycrystalline silicon, so that incident light on the deep groove is substantially completely reflected, optical crosstalk can be avoided, optical resolution and sensitivity of a pixel are effectively improved, and performance and reliability of a chip are improved.