To study the effect of triacontanol on the growth of gametophytic blades of the wild type strain (WT) in Pyropia haitanensis, the blades of WT strain were immersed in triacontanol solution at concentration of 1×10^-7, 3×10^-7, 5×10^-7 and 7×10^-7 for one day static culture respectively. Then the blades were transferred to aeration culture with normal culture medium. The results showed that, after 25 days of culture,3×10^-7 had the best treatment effect, 5×10^-7 took the second place,1×10^-7 triacontanol treated blades almost had no difference with the control group, while 7×10^-7 inhibited the growth of blades. Compared to the control group, the mean length of blades strain treated with 3×10^-7 triacontanol increased by 94.92%, and chlorophyll a, phycoerythrin and phycocyanin increased by 26.00%, 92.88% and 84.89%, respectively. The effect of triacontanol on the growth of blades of the WT strain showed initial increase then decrease, and the promotion effect could maintain about 20 days after treatment. These results revealed that 3×10^-7 triacontanol could constantly accelerate the growth of blades, and increase the contents of photosynthetic pigment and chromoproteins in the blades.