The invention discloses a specific culture medium for a lung tumor organ and a stentless 3D culturing method. The specific culture medium is prepared from the following components: FBS, double antibody, N-2, Noggin, B-27, EGF, FGF-10, Y-27632, A 83-01, SB202190, N-acetylcysteine, HEPES, Glutamax, IGF-1, hydrocortisone and Advanced DMEM/F12. The culturing method comprises the following steps: adding a tumor cell into a low serum culture medium, re-suspending the tumor cell, inoculating the tumor cell into a culture vessel, adding the specific culture medium into the culture vessel, changing thespecific culture medium once a day, and performing culturing until an organoid is formed. According to the culture medium and culturing method, a tumor organoid can quickly generate, can be stably cultured for a long time, is regular in spheroid form and has uniform and controllable size, and the heterogeneity of a tumor tissue of a patient can be well maintained in vitro.