How to carry out ecological protection and restoration is a practical problem faced in the construction of national parks. The implementing natural restoration is considered an important measure for conservation and restoration, but changes in ecosystem elements still need to be clarified during the restoration process. This study took the Yinggeling area of the Tropical Rainforest National Park as the object. We constructed forest restoration gradient by selecting normally managed rubber forests, 2-year rubber forests restored after abandonment, 10-year secondary forests, 30-year secondary forests, 60-year secondary forests and mature forests. Changes in plant diversity and soil properties are explored along with the forest restoration process. The results showed that plant richness and Shannon-Wiener diversity index first increased and then decreased with the forest restoration process. More specifically, plant diversity reached the highest after 30 years of restoration and tended to be stable after 60 years of restoration. Soil organic matter and total nitrogen first decreased and then increased, but total phosphorus showed a decreasing trend. The correlations between plant richness and Shannon-Wiener diversity index were insignificant with soil organic matter and total nitrogen, but they were significantly negatively correlated with total phosphorus. These results clarify the number of years required to restore plant diversity using rubber forests as the starting point for restoration, and confirm the relationship between plant diversity and total soil phosphorus during the restoration process. This study provides support for evaluating the effects of ecological conservation and restoration in tropical rainforest national parks.