The spectral features of a laser diode (LD) pumped dual-frequency Nd:YVO_4microchip laser with tunable frequency difference are investigated.To the field width of fluorescence spectum of the laser gain medium,the feature of output laser spectrum is mainly related with the pumping power,positi on of pumping,cavity length and other parameters.By means of controlling the related parameters,the relative f requency difference of output laser between the different wavelength spectrum peaks can be adjusted.The exper imental results show that when the LD pumping current is 14.5A,pumping light and resonant cavity mode can achi eve good matching,a stable dual-longitudinal mode is output,and the corresponding frequency difference ca n reach more than 90GHz.Changing the pumping parameters corresponding frequenc y difference between 92.22GHz and 94.24GHz,when increasing the resonator cavity length,which can decrease the laser longitudinal mode interval and output three longitudinal modes,the minimum frequency between two frequency peaks reaches 26.5GHz.