In this paper, we investigate several methods to resolve integer ambiguities in Global Navigation Satellite Systems (GNSS) carrier phase positioning applied by Kalman filter. Especially, we focus on integration methods of Least squares AMBiguity Decorrelation Adjustment (LAMBDA) [1, 2] method and Kalman filter. They are compared from theoretical and experimental points of view, and their characteristics and performance are investigated. We conduct experiments using real receiver data, and evaluate the integer ambiguity resolution performance. Based on the results, we show a guideline to resolve ambiguities with Kalman filter.