The invention relates to a solar battery in the space energy technology field, in particular to a solar battery and preparing method for applying diamond membranes in special structures. The main structure of the diamond membrane solar battery comprises a cathode and an anode, the cathode structure is that pyramid type diamond small cones with sizes of 3 to 4 mu m in small holes are evenly distributed on the surface of a crystalline silicon, the pyramid type diamond small cones and a sheet metal are combined to form the cathode, the opposite side of the cathode is added with a layer of black-body heat-sink materials, and flat-plate metals are used as the anode. The working principle of the solar battery is that a light-gathering device is used to gather sun rays on the black-body heat-sinkmaterials of the opposite side of the anode and heat the anode up to more than 1000 DEG C for emitting a large amount of electrons out of pointed ends of small cones, under the function of an impressed electric field, electrons move to the metal anode to form electric currents. In the diamond membrane battery provided in the invention, the photoelectric transformation efficiency can lift to 50%,which is capable of bearing the high temperature of more than 500 DEG C without damaging and of enduring space radiation.