With oil exploration and development to deep complex formation and deep water, drilling engineering design and construction become more and more sophisticated and the drilling engineering projects more and more depend on the drilling engineering software from design, real-time construction monitoring and optimization to experience review. The integrated drilling engineering software for drilling planning and real-time optimization has been developed in order to accomplish the needs of drilling design, analysis, construction optimization and solve the problem that different drilling software for different domain is isolated in development and applications. This article described the system design, key technologies, main features and applications on the integrated drilling engineering software. Details of the integrated drilling engineering software are elaborated on the subsytems of formation pressure analysis and prediction, rock mechanics analysis, wellbore trajectory design, drilling fluid design and analysis, drill string mechanics analysis, cementing engineering design and analysis, underbalanced drilling design and analysis, real-time drilling data management, real-time drilling monitoring and optimization. The integrated drilling engineering software developed the unified database for both drilling design and real-time construction and unified drilling engineering software integration platform with module dynamically loading technology based on abundant shared two-dimensional, three-dimensional visualization modules. Every drilling software subsystems on the integration platform can share data with each other and the drilling design can be compared with the construction data for analysis and optimization, so the entire drilling engineering workflow can be accomplished in this integrated drilling engineering software without inputting data repeatedly. Hundreds of drilling design and construction optimization applications on the integrated drilling engineering software in some typical oilfields of China demonstrate that it has rich functionalities, precise analysis and effective optimization, and can reduce the downhole complex and enhance the safety of drilling engineering.