The distribution and migration ability of weak gel directly affect the effect of oil displacement by its application, but the conventional studies in normal cores are difficult to achieve the intuitive observation of gel distribution, and reflect less on the influence of heterogeneity. The flooding experiments of weak gel and CT scanns were designed in a long sand-pack, large size visualized heterogeneous model and a heterogeneous core to study its distribution and migration depth of weak gel in those porous media. The results obtained from the long sand pack show that before the final gelation time of 12.0-14.0 h, the dynamic injection pressure of the gel has increased significantly to a highest 37.5 MPa. On the one hand, it proves the occurrence of dynamic gelation, and on the other hand, it shows that the migration resistance of the gel is greatly increased and the flow difficulty occurs earlier than that final gelation time，as a result, this time can not accurately reflect the fluidity of the gel solution in porous media. During the injection of gel solution and subsequent water flooding, gel can be transported, but the distance is relatively small (total model length 21.5 m, colloid injection 0.0-4.2 m, effective plugging 4.2-8.5 m by transport during subsequent water), and a very large displacement pressure (15.0-37.5 MPa) is required. The results from a visualization heterogenous model indicate that the plugging depth by the first injection of gel is approximately 27.0 cm. When the subsequent water, the second and third rounds of gel are applied, the gel from the initial round does not significantly migrate due to the high plugging strength of gel, the bypass flow of those followed displacing agents and the consequent slightly increased injection pressure. As a result, the plugging depth by those the three rounds of gel is limited to 43.3cm from the total length of the model 200cm. The fluid distribution results in the heterogeneous core model also prove that weak gel can hardly migrate significantly after gelation under heterogeneous conditions, and weak gel plays more of a "profile control" role rather than "flooding associated with dynamic profile control ".