The invention discloses a software development method and a software development system. The method comprises an initial stage, a refinement stage, a construction stage, a handover stage and a maintenance stage. The construction stage includes software development, software development comprises the following steps that 1, initialization modeling is conducted on software development, the initialization modeling unit mainly comprises a basic processing flow of a software system, an organization structure of the system, module division, function distribution, interface design, operation design,data structure design and error processing design, and a basis is provided for detailed design of software; 2, a detailed modeling unit for software development is formulated on the basis of the initial modeling unit;. According to the method, a perfect logic structure is made for a software development system from early-stage software development planning, preparation work, development work, installation and release, later-stage maintenance and the like, it is ensured that in the software development process, development errors are reduced, the uncontrollability in software development is reduced, and the software development efficiency is improved.