Objective To investigate the effect of different concentrations of Matrigel on ectopic subcutaneoustransplanted tumor of Lewis lung cancer in mice. Methods Twenty-four C57BL/6J Nifdc mice were randomly divided intoa Lung cancer group, 50% Matrigel group, 75% Matrigel group, and 100% Matrigel group, with six mice in each group.Lewis lung cancer cells (LL/2) were mixed with 0%, 50%, 75% and 100% Matrigel at a volume ratio of 1 ∶ 1. The micewere injected subcutaneously under the armpit of the right forelimb. The weight, diet and volume of drinking water of micein each group were measured every day. The tumor formation time, tumor formation rate and tumor size were observed. Thelong diameter and short diameter of the tumor were measured every day after the formation of the tumor, and the change intumor volume was calculated. The animals were terminated on 15 days after tumor inoculation, the tumor tissue wasremoved and weighed, and the pathological changes of the tumor tissue were detected by HE staining. Results Comparedwith the Lung cancer group, the weight of the 75% Matrigel group increased significantly from the second day of modeling( P < 0. 05 or P < 0. 01). The weight of mice in the 100% Matrigel group increased significantly from the 10th day ofmodeling ( P < 0. 05 or P < 0. 01). The average diet of mice in each group decreased eight days after modeling, and thevolume of drinking water showed an upward trend. The tumor formation rate in each group was 100%. Mice with Matrigelhad earlier tumor formation time, faster tumor growth rate, and a larger tumor than those without. Among them, the 75%Matrigel group had the fastest tumor volume growth and the greatest tumor weight, (1358. 88 ± 388. 14) mg, comparedwith the Lung cancer group ( P < 0. 05). The tumor volume growth and tumor weight in the 100% Matrigel group were thesecond greatest, and the tumor weight was (1142. 37 ± 423. 08) mg, which was significantly different from that in theLung cancer group ( P < 0. 05). The tumor volume growth and tumor weight in the 50% Matrigel group were the smallest,(808. 83 ± 393. 41) mg. The result of HE staining show that, compared with the Lung cancer group, the tumor cells withMatrigel group had vigorous growth, a clear outline, large nuclear volume, and significantly more vascular components inthe stroma of the tumor tissue. Conclusions Matrigel can stabilize the tumor formation rate, accelerate tumor growth, andincrease the tumor formation volume. Under the condition with 75% Matrigel, the tumor growth was the fastest, the tumorvolume was the largest, and the tumor was uniform.