In order to improve the efficiency and accuracy in application of CATIA in ship modeling and evaluation, the VB programming language is used to conduct the CATIA secondary development and establish the interface. It is not only easy to enter the rudder parameters and create the surfaces of rudder and heel quickly, but also able to set the draught height, seawater density, shell thickness, etc., so as to count up the main hull elements, such as principal dimensions, form coefficients, dimension ratio, etc. and output them automatically, which can greatly enhance the working efficiency of multischeme modeling and evaluation. The program idea and key program codes are given, which can be used as reference for the related software development.