The increase in costs and the decline in profits have seriously affected the economic benefits of bamboo forests and bamboo farmers' enthusiasm for production. It is imperative to study new management techniques and methods of bamboo forests. By controlling the cutting width and harvesting area, we observed the five different widths (3 m, 5 m, 8 m, 12 m, and 15 m) strip harvesting bamboo forest in the state-owned forest farm of Yixing in Jiangsu Province after one-year recovery period. The response mechanism of species diversity characteristics to the width and recovery state of bamboo forest were analyzed. The results indicated that (1) there were 110 species of 95 genus in 53 families of undergrowth species in the study area (76 species of shrubs of 64 genus in 37 families and 34 species of herbs of 30 genus in 18 families), such as Rosaceae, Compositae, Euphorbiaceae, Rubiaceae, Liliaceae, Labiatae, Gramineae, and Verbenaceae. (2) The species richness decreased with the increase of canopy density of bamboo forest. The harvesting significantly promoted species richness (especially woody plants), with the most increased species in the 8 m and 15 m width plots. (3) The strip harvesting promoted the species diversity of undergrowth, but reduced the species uniformity. The Shannon-Wiener index, Simpson index and Gleason species richness of the 8 m and 15 m width plots were better than those of the sample plots. The species evenness of undergrowth in the five width strips plots were smaller than that of the sample plots. The keeping plots had higher species evenness than the cutting plots in the same width plot type. (4) Harvesting operations significantly promoted the biomass of undergrowth in 8 m and 15 m cutting plots, but had no significant effects on the keeping strip plots.