In this paper, theo ptical spectrum of several new infrared ultrafast saturable absorption dyes, the measurement of their relaxation time in picosecond region are mainlly described and the experimental technology are discussed. The time resolution of the setup has been determined being shorter than 1 ps by the autocorrelation measurement. The measured absorption recovery time of four kinds of the dyes are form 5 to 9 ps. Their optochemical stability is much better than Kodak 9860.