The objective of the doctoral thesis was to obtain scientific research results on the possibilities to develop a higher precision geoid model of Latvia using various methods and data sets - global Earth’s gravity field models, gravimetric, GNSS/levelling and astrogeodetic. The task of the thesis was study and analysis on the possibilities of using the most recent global gravity field models for the improvement of the national geoid model of Latvia; study on the use of gravimetric method by the Royal Institute of Technology (KTH) under the conditions of Latvia and analysis of results; development of a new Latvian geoid model with the use of Digital Finite Element Height Reference Surface (DFHRS) method and analysis of results; analysis of astrogeodetic method and opportunities of its application, development of a digital zenith telescope optics and telescope prototype, analysis of experimental vertical deflection measurements. Topicality of the thesis is characterized by the extensive use of GNSS technology, as well as accurate height determination requirements by using this technology. It is required by high accuracy standarts of civil engineering, geodesy, cadastre and other industrial fields. High precision geoid model is an important component to provide an accurate determination of heights using GNSS technology. Currently Latvian gravimetric geoid model LV'98 is widely used and its precision reaches 6-8 centimeters, so there is a need for more accurate geoid model for the operative determination of normal heights. In the thesis, author considers three methods of Latvian national geoid model computation: KTH method, DFHRS method and astrogeodetic method. The author of the thesis has considered possibilities of Earth's global gravity field model application, as a result approximate vertical deflection computation in Latvian territory was carried out using Earth's global gravity field model data. Using the KTH method gravimetric geoid model for the whole Latvian territory was developed, computation was made by experimenting with the input data and sperical integration parameters. Using the KTH method and latest gravimetric measurements and Earth's global gravity field model data gravimetric geoid model for Riga region was developed. Using the DFHRS method Latvian geoid model with a 1.6 cm mean square error was developed. With the participation of the author prototype of digital zenith telescope and its data processing algorithm was developed to use astrogeodetic geoid determination method. In the thesis, description of tasks, course of development, measurements, data processing, analysis and research assessment of the above-mentioned scientific subject is given in Latvian on 127 pages, 92 figures and 7 tables. Thesis consists of six chapters, conclusion and used information sources list consisting of 121 entries.