大地水准面或似大地水准面是获取地理空间信息的高程基准面，在高精度、高分辨率(似)大地水准面模型的支持下，利用GPS技术可以直接测定正高或正常高，从而取代传统复杂的水准测量方法，使得平面控制网和高程控制网分离的传统大地测量模式成为历史。因此，精化大地水准面是一个国家或地区建立现代高程基准的主要任务之一。大地水准面精化是大地测量、地球物理等学科研究的重要内容之一，同时也是一项重要的基础测绘项目。确定厘米量级的局部（似）大地水准面是当今大地测量学研究的热点。它将为基础测绘、数字中国地理空间基础框架、区域沉降监测、环境预报与防灾减灾、国防建设、海洋科学、气象预报、地学研究、交通、水利、电力等多学科研究与应用提供必要的测绘服务，具有特别重要的科学意义以及巨大的社会效益和经济效益。 本文首先系统地研究了精化大地水准面各种方法的原理，然后分别对其中的几何法和重力法进行了详细的讨论和研究。在几何法中分别用传统的移动曲面、多面函数以及神经网络法试算和分析各自的应用范围，进行精度和实用性比较；在重力法中通过实例，试算并分析了由位系数确定大地水准面差距的精度及其特点，并结合地球位模型的优点，研究地球位模型与其他各种方法的结合：讨论了地球位模型与神经网络法结合，从而拓展后者的使用范围；重点研究了计算区域大地水准面的标准算法(移去～恢复法)的原理和数学模型。 结合测区GPS水准资料，采用多项式曲面拟合模型、移动曲面拟合模型和多面函数模型，用matlab自编程序做了拟合试验和精度分析，得出相关结论，取得良好效果，拟合的区域似大地水准面可应用于GPS大地高与正常高之间的转换。之后，介绍了地球重力场模型理论，研究了如何利用地球重力场模型和GPS水准数据，采用移去～恢复方法计算区域似大地水准面，进而求解正常高的方法，并结合实例将其与常规拟合的结果进行比较，对其在生产应用中的可行性进行了分析。

Geiod or quasi-geoid is a height datum for acquiring geospatial information. If the geoid or quasi-geoid model is given, GPS can be used directly to determine orthometric height or normal height, which can take the place of the traditional geometric leveling and make the seperation mode of plane control network and elevation control network in traditional geodesy become a history. Therefore geoid refining is one of important missions for the establishment of the height datum in a country or a region. Precise determination of local geoid is the importing issue of some field .such asgeodesy and geophysical .and so on. And same time, it also is a import project of basemap up date, Regional geoid determination with centimeter-level precision is the geodesy research hotspot. It will provide mufti-disciplinary research and application such as base map up date ,digital China geo-spatial framework, local monitoring on settlement ,environment forecast ,disaster prevention, national defense construction,ocean science, weather forecast, earth science research, traffic, water resources,power with essential surveying and mapping service, has significant scientific significance and tremendous economic and social benefit. At first the article describes basic theory and principles of precise determination of local geoid. Then discuss and make a research about geometrical method and gravitymethod at length, respectively. In the geometrical method ,compute and analyze the applicable area of the moving curved surface fitting, multiple curved surface fitting, Neural Network ( NNT ) ,compare the precision and applicable area. Combining measuring region GPS/leveling data thesis adopts the maul trinomial surface： fitting model and move curve surface fitting model and Har function interpolation model, author has developed a MATLAB program to do the test and analyze its accuracy and draws several satisfied conclusion’s. The fitting regional quasi-gieod can be applied into the shift between GPS height and normal height. Then, it introduces the theory of global geopotential model and studies how to determine regional quasi-geoid with remove-restore method, GPS/leveling data and global geopotential model, gaining the; normal height.