The spectra of the laser pulses output from a short cavity dye laser (SCDL) and then amplified by a dye laser amplifier were observed experimentally. The major spectral parameters of the laser spectral of the longitudinal modes (LM) were measured. The change in spectral features including spectral envelope, frequency pulling, and number of the LM etc., are compared. Under certain conditions, the dye amplifier can produce one or more new LMs in the multi LM amplification, while in the other cases, the number of the LM output from the amplifier remains unchanged. There are striking resemblances between the new LMs and the initial modes, for example, the new modes have properties in frequency pulling, collinear and codirection propagating. In the mode coupling and generating there exists frequency pulling, this implies that there is photon frequency mismatch and photon energy unconserves in total resonant four wave mixing (FWM) in dye amplifier.