The purpose of this research is to determine growth differences of Sargassum sp., were cultured with different cultivation systems in the Ekas Bay of East Lombok. This research is an experimental research. The sample in this research is Sargassum sp. of cultivated crops with different cultivation systems, such as : floating raft and raft basic stakes. Processing date was performed by using a processing date computer program package SPSS 16. Hypothesis testing is done by using t-test polled variance, with a significance level of 0.05 and a level of valid 95 %, in order to obtain t count 11.974 > t - table 1,987, or based on the value of the indicated probability, probability-count obtained 0.00 < 0.05 probability- table , so that Ho is rejected and Ha accepted , this means that there are differences in the growth of Sargassum sp. were cultured with different cultivation systems.