Abstract: Forest health management is one of the research hotspots at the present stage, and the key is to maintain and create the optimal forest spatial structure. The forest spatial structure (FSS) and optimal species composition were studied with the commonly-used forest spatial structure parameters (i.e. mingling, neighborhood comparison, neighborhood pattern, forest spatial structure index (FSSI), and forest spatial structure distance (FSSD)) based on the data of 44 plots in Daxing'anling Mountains of northeast China, which were collected in the 2011 and 2012. The results showed that the horizontal distribution pattern of natural Larix gmelini (LG), coniferous mixed (CM) and coniferous-broadleaved mixed (CBM) stands mainly followed the random distribution, and the Betula platyphylla (BP) natural forest followed the typical cluster distribution. The tree growth of the four forest types were moderate as a whole,in which L. gmelini was at the dominant position and the others species were squeezed with different degrees. And the mixed degree of L. gmelini was reduced with the increase of its dominance, the other species had a higher mixed degree of species. As a whole, the mixed degree of species for LG and BP forest were relative lower (0.20 and 0.07), but the two mixed forest types were higher (0.45 and 0.56). Significant difference of FSS was found among the four main forest types in study area, the order was CBM>CM>LG>BP. From the viewpoint of maintaining and creating the optimal forest spatial structure, it was found that the proportion of L. gmelini accounted for 80% of the whole forest was the optimal species composition for the LG forest.