The invention relates to a method for quantitatively representing a sandstone reservoir hole throat structure by nuclear magnetic resonance coupling constant-speed mercury injection. The method for quantitatively representing the sandstone reservoir hole throat structure by nuclear magnetic resonance coupling constant-speed mercury injection comprises the steps of selecting a full-size core of a target sandstone reservoir, drilling a small rock sample, and performing nuclear magnetic resonance experiment to obtain a T2 relaxation time duty ratio distribution curve; performing constant-speed mercury injection on the small rock sample to obtain a constant-speed mercury injection hole throat duty ratio distribution curve; coupling maximum relaxation time T<2max> and maximum hole throat radiumr of the same small rock sample to obtain surface relaxation rate Phi of each small rock sample so that the surface relaxation rate Phi is used as the surface relaxation rate Phi of the target sandstone reservoir; and performing calculation to obtain complete effective hole throat radius duty ratio distribution map according to a nuclear magnetic resonance principle. By the method, thecomplete and effective hole throat relaxation time distribution characteristic can be non-destructively detected, the complete and effective hole throat radium duty ratio distribution map of the reservoir sandstone is obtained, and the quantitative representation of the effective hole throat structure distribution of the sandstone reservoir is achieved.