Software-reliability evaluation can estimate and predict reliabilities of software . For the purpose of solving the problems in software prediction process, a practical software-reliability prediction method is proposed to give better software reliability predictions. In this method, a model is selected by analyzing and improving models' prediction quality. U plot, Y plot and logarithm PLR plot are used to analyze models' prediction quality,recalibration method and combination method are used to improve it. A software-reliability analysis tool based on this method is then developed. With this tool one can do predictions using several kinds of raw software reliability models, analyze prediction quality and improve prediction quality of raw models.