Urban square landscape construction has important value in urban development, environmental protection, aesthetic appreciation and so on. The introduction of computer aided technology to promote the digital transformation of landscape planning and design can further improve the efficiency and quality of planning and design. The urban square landscape design and planning project is taken as the main body of the study. Specific design and analysis were carried out for the experimental platform construction, three-dimensional object realization and urban square landscape design model construction scheme, and AHP was used to establish a virtual reality urban square landscape design evaluation model. The final evaluation results show that using computer technology and software can complete the construction of virtual reality scene with high efficiency, accuracy and quality. Based on the evaluation model of city square landscape design and integration of CAD rendering technology, the three-dimensional city square landscape design simulation system designed in this paper closely integrates. production of domestic plant database, suitable for city square landscape terrain design, parametric design of city square ancillary facilities, etc., well meet the needs of professional designers, fully fill the blank of domestic city square professional software.