When the early-age concrete is exposed to a negative temperature environment, the internal relative humidity will continue to change under the action of ambient temperature and humidity, affecting its physical properties, which in turn leads to changes in the performance of the concrete structure. Based on this, the variation law of relative humidity at different depths from the upper surface of the concrete with different initial humidity under sealed and unsealed conditions of early-age concrete in cold regions was studied by experiments. The results show that the influence of ambient temperature on the internal relative humidity of concrete is greater than that of ambient humidity. The temperature-relative humidity change process of each specimen during the test can be divided into five stages. For the same initial humidity of the specimen, the closer to the upper surface, the greater the relative humidity change, the greater the impact of the environment; At the same depth from the upper surface, the higher the initial humidity, the greater the relative humidity change, and the greater the environmental impact.