The operating characteristics of a colliding pulse mode-locked ring dye laser using DODCI and DQOCI dye as saturable absorbers are studied. Measurement results of the dependence of the pulse width of the mode-locked pulses, the stability range of laser for stationary single-pulse operation and the threshold pumping power on the concentration of the absorber dye are given. Stable pulses with duration of 0.12 psec and peak power of 1kW can routinely be obtained with this laser at a low pumping power (about 2 W). The results of the spectrum-resolved SHG correlation measurements of the mode-locked pulses also axe presented, which confirmed the presence of frequency chirping in the pulses. It has bean found that by using DQOGI dye as the saturable absorber the spectrum of tlie laser output consists of two separate parts located in the yellow and red regions respectively and when the oscillation in yellow is supressed the modelocking stability is improved and the output pulses exhibit clean pulse shapes with much reduced wings.