Lentinan is a β-(1→6) branched β-(1→3)-glucan derived from Lentinula edodes mushroom. It has been developed as an adjuvant to cancer chemotherapy and clinically used in Japan and China. Up to date, six lentinan injections or powders for injection produced by individual manufacturers were widely used in clinic in China. Since antitumor effect of lentinan is highly related to its structure, conformation and molecular weight, quality evaluation of lentinan injection produced in China is crucial to ensure its efficacy, which has never been performed. In this study, absolute molecular weights and their distributions of lentinan in multiple batches of injections from different manufacturers in China were firstly determined through a high performance size exclusive chromatography (HPSEC) combined with multiple angle light scattering detection (MALSD) and refractive index detection (RID). Enzymatic (β-1,3-D-glucanase) digestion characters and triple helical conformation of lentinan were also investigated. The results showed that quality consistency of lentinan injections from different manufacturers in China was poor, which should be greatly improved to ensure their safety and efficacy.