Abstract: The variation in seedling height, ground diameter growth and the variation in anisotropic growth indices of 1–3a Pinus yunnanensis seedlings from different seed sources were studied to gain insight into the differentiation variation characteristics and anisotropic growth relationships of P. yunnanensis seedling growth among seed sources.Statistical analysis and allometric growth relationship analysis were conducted on the growth of 1–3 years old P. yunnanensis seedlings in terms of height and ground diameter. A comparison was made between the growth differentiation characteristics and the allometric growth index of P. yunnanensis seedlings at different ages from 3 different provenances.The results showed that the seedling height and ground diameter of P. yunnanensis seedlings varied significantly among provenances at different seedling ages, and the variation degree of traits decreased with the growth of seedling ages, and there was a very significant correlation between traits. The variation coefficient of seedling height within provenances first increased and then decreased with the increase of seedling age, with the overall fluctuation range of 32%–50%, and the overall fluctuation range of ground diameter variation coefficient was 33%–48%, which showed a decreasing trend with the increase of seedling age. Both traits were dominated by the variation within provenances, and the factors within provenances of the variation sources were weakened with the increase of seedling age. There was abundant variation among different provenances, among which, the mean coefficient of variation of seedling height growth of Xinping provenances was 46%, higher than that of the other 2 provenances. There was a significant allometric growth phenomenon among P. yunnanensis seedlings of different provenances and different seedling ages, and the allometric growth index was variable. There were abundant differentiation and variation in seedling height and ground diameter, and the differentiation degree of characters was obviously affected by time. The 2 traits of the seedlings of different provenances are mainly intra-provenance variation, and the variation degree of the seedlings of different provenances is different. The seedlings of different ages will adjust their growth strategies according to their own growth conditions to adapt to the competition for resources. The allometric growth relationship of seedlings from different seed sources showed significant differences between different seedling ages, and the allometric growth index showed significant differences with common slope. With the increase of seedling ages, the allometric growth relationship model of seedlings from height to ground diameter changed from an elastic self-similar pseudo-model to a geometric similarity model, which was consistent with the result that the allometric growth index of small individual plants was close to 1. Allometric growth index changes with the growth of seedlings, but is not constant. Seedlings are affected by their own genetic quality and adaptability to the environment.