Abstract: The responses of nucleic acid and protein in leaf were analyzed objecting to two Chinese fir clones with different resistance to salicylic acid stress. The results showed that, in most situations, salicylic acid stress inhabited the DNA synthesis of endurance type clone and promoted its RNA synthesis and the effect characteristics on the sensitivity type was opposite to the endurance type. At the initial period all concentration levels had higher stimulatory effects on the protein content of the sensitivity type than that of endurance type. At the intermediate and later periods, the stimulatory effect on sensitivity type appeared decreasing trend, while the stimulatory effect on endurance type increased continuously with the increasing concentration. Those evidences hinted there were different genetic expression modulations between the two resistance types. The RNA and protein contents of endurance type increased with the increasing stress intensity, which indicated that it aroused more protein to participate in the stress response to enhance its resistance.