Abstract: Gloiopeltis furcata, an important economic red macroalga, has been severely depleted due to human disturbances. Taking the natural G. furcata populations around the Xiaoheishan Island of Shandong, China as test objects, this paper studied the spatiotemporal variation pattern of their biomass and length and related affecting factors. The twoway ANCOVA showed that at island scale, both the subbottom and the Baardseth index had significant effects on the G. furcata biomass and length. The steady subbottom and the high Baardseth index were beneficial to the G. furcata growth. At microhabitat scale, wave action and tidal level had significant effects on the G. furcata biomass and length. Wave wash and moderate tidal level promoted the G. furcata growth. The oneway repeated measurements ANOVA showed there existed seasonal variation of G. furcat biomass and length. The optimal growth period of G. furcata was from March to April, with the peak values of biomass and length appeared in late spring and early summer.