Many studies have shown that mental simulation may occur during language comprehension. Supporting evidence is derived from the matching effects in the sentence-picture verification (SPV) task often used to assess mental simulations of object properties, such as size, orientation, and shape. However, mixed results have been obtained regarding object colour, with researchers reporting matching or mismatching effects. This study investigated the impact of colour information clarity within sentences on the process of mental simulation during language comprehension. Employing the SPV task and using novel objects, we examined whether there is a mental simulation of colour after excluding typical/atypical colour bias and how varying levels of colour information clarity in sentences influence the emergence of matching effects at different stages of comprehension. To address these issues, we conducted two experiments. In Experiment 1, the participants read normal sentences and subsequently engaged in picture verification with a novel object after a 500 ms delay. In Experiment 2, the participants encountered sentences containing both clear and unclear colour information and, after either a 0 ms or 1500 ms interval, completed picture verification tasks with a novel object. Null effects were found in the 500 ms condition for normal sentences and the 0 ms condition for unclear colour information sentences. A mismatching effect appeared in the 0 ms condition after clear colour information sentences, and a matching effect appeared in the 1500 ms condition for all sentences. The results indicated that after excluding colour bias, the participants still formed mental simulations of colour during language comprehension. Our results also indicated that ongoing colour simulation with time pressure impacted the participant responses. The participants ignored unclear colour information under time pressure, but without time pressure, they constructed simulations that were as detailed as possible, regardless of whether the implicit colour information in the sentence was clear.