With the development of laser technology, the laser wavelength has been the primary standard of length measurement. The measurement of laser wavelength is studied widely in the world. In fact, the accuracy is different when measured in the air and vacuum. The measurement accuracy of laser wavelength is high when measured in vacuum, such as beat frequency method, its precision can meet 10<sup>-15 </sup>order of magnitude. However, most of length measurement are taken place in air which influenced by environmental factors such as temperature, pressure, humidity and air ingredient. The research of how to enhance the measurement precision in air is meaningful. There are many general methods for measurement of laser wavelength include Edlen empirical formula method, the extraction method (the refractive index interferometer), F-P etalon method, and grating diffraction method, etc. By comparing and analyzing these methods, among them the Edlen formula method is the most simple and practical, the measurement result and analysis demonstrate the measurement method can achieve the precision of 3× 10<sup>-8</sup>.