The invention discloses a preparation method for a perovskite solar cell absorption layer capable of improving photoelectric properties through controlling an annealing pressure intensity atmosphere. The preparation method comprises the procedures: carrying out reagent preparing, carrying out cleaning, carrying out spin coating and carrying out annealing, i.e., firstly weighing methylamine iodine and lead iodide which are in the mole ratio of 3: 1, dissolving methylamine iodine and lead iodide in N,N-dimethylformamide in a mixed manner, and carrying out heating stirring for 10-14 hours at the temperature of 50-70 DEG C, so as to obtain a spin-coating solution for later use, wherein the mass fraction of N,N-dimethylformamide is 25-45%; fixing a substrate, which is cleaned until the substrate meets spin-coating requirements, and uniformly coating the substrate with 35-50 microliters of the spin-coating solution under nitrogen protection in a spin-coating manner, so as to obtain a uniform and stable coating film; carrying out annealing on the coating film attached substrate for 12-60 minutes at the temperature of 100-120 DEG C and the pressure of 4.5mTorr to 560Torr, and then, cooling the substrate to room temperature, thereby obtaining the target perovskite solar cell absorption layer. The perovskite solar cell absorption layer prepared by the method has the thickness of 200-500nm, and the electron mobility of the absorption layer is superior to that of absorption layers prepared by other methods, so that the efficiency of solar cells is increased.