The software industry has had significant progress in recent years. The entire life of software includes two phases: Production and Maintenance. Software maintenance cost is increasingly growing and estimates showed that about 90%, if software life cost is related to its maintenance phase. Extraction and considering the factors affecting software maintenance cost help to estimate the cost and reduce it by controlling the factors. Cost estimation of maintenance phase is necessary to predict the reliability, improve the productivity, project planning, controlling and adaptability of the software. Though there are various models to estimate the maintenance cost of traditional software like COCOMO, SLIM, Function Point etc., but till now there is no such model to estimate the maintenance cost using fourth generation language environment. Software maintenance will continue to exist in the fourth generation environment, as systems will still be required to evolve. In this kind of situation there is needed to develop a model to estimate the maintenance cost using fourth generation environment. We propose a systematic approach and development for software maintenance cost estimation model using fourth generation language environment on the basis of COCOMO II. This model is based on three parameters: SMCE with Fourth Generation Language Environment, ACT (Annual Change Traffic), Technical and Non-Technical factors which affect the maintenance cost. The favorable results closely matching and it can be achieved by using model implementation.