The invention relates to rubber modified asphalt. The rubber modified asphalt comprises the following raw materials in parts by weight: 22-33 parts of matrix asphalt, 2-5 parts of an interface stabilizer and 40-60 parts of rubber powder. A preparation method of a rubber modified asphalt powder formula comprises the following steps: firstly, heating the matrix asphalt to the temperature from 145 DEG C to 165 DEG C and uniformly stirring to uniformly heat the matrix asphalt so as to obtain primary stirring liquid; secondly, rapidly heating the primary stirring liquid to the temperature from 175DEG C to 190 DEG C, adding a required amount of rubber powder, and uniformly stirring to obtain secondary stirring liquid, wherein the stirring time lasts for 45 seconds to 60 seconds; thirdly, pumping the secondary stirring liquid into a high-speed stirring kettle, and grinding and stirring to obtain a mixture, wherein the stirring time lasts for 1 minute to 2 minutes; and fourthly, adding the ternary stirring liquid into a development tank, then adding the interface stabilizer for development, and uniformly stirring to obtain the rubber modified asphalt, wherein the stirring time lasts for 45 minutes to 60 minutes. By the invention, the problems of high requirements on workability, viscosity and uniformity of existing rubber modified asphalt in an implementation process can be solved effectively.