Simulation methodology is the important basic theory of Simulation Science and Technology (SST). A four-dimensional simulation methodology framework including specialized subject, target, logic and knowledge was established. The core of simulation methodology with three levels of thought methods, theory methods and technology methods was summed up. The guiding effect of dialectical materialism and system theory as simulation thought basis was discussed. Simulation methodology including modeling methodology concerning abstract and mapping, simulation methodology concerning model experiment and application methodology directed by target was proposed. The general methods of simulation modeling, simulation experiment and simulation application were discussed. And all the simulation methods were classified by size and complexity of simulation object, property of system model, realization means of simulation system, structure of simulation system and relation between simulation clock and actual clock.