The temperature characteristics of 808 nm InGaAsP-InP SQW lasers have been investigated in a heat-tight system by analyzing their structure. It is shown that the power and the slope efficiency of the devices decreases from 1.74 m to 0.51 W and 1.08 mW/mA to 0.51 mW/mA in the temperature range of 23～70℃,respectively. Lasing wavelength shift coefficient dλ/dT is 0.44 nm/(℃). The characteristic temperature T₀ of 325 K is experimentally obtained. The thermal resistance of the chip,determined experimentally,is 3.33℃/W.