Researching the relationship between forest landscape pattern and the damage caused by herbivorous insects provides an important theoretical basis for constructing landscape ecological security pattern and realizing ecological regulation of pests. A field survey was carried out to obtain the data on damage caused by herbivorous insects in the Irtysh river riparian forest, and landscape index was extracted based on remote sensing data. This study analyzed the effects of forest landscape pattern and landscape characteristics of forest land, farmland, grassland and wasteland on the damage caused by two kinds of herbivorous insects, at the level of landscape and landscape type respectively with Linear Mixed-Effects Models. The results showed that landscape fragmentation was the key factor which compounded the damage caused by two herbivorous insects in the Irtysh river riparian forests, but the responses of leaf chewers and leaf miner to the landscape pattern were not completely consistent. At the landscape level, the damage caused by leaf chewers was significantly positively correlated with landscape richness and landscape connectivity, while the damage caused by leaf miner was significantly negatively correlated with mean patch area. At the level of landscape type, the damage caused by herbivorous insects in the Irtysh river riparian forest was positively correlated with the number of patches in the forest. The increase of cultivated land area led to the increase of population density of leaf miners. The landscape cohesion index of wasteland and the average patch fractal dimension of grassland were significantly positively correlated with the rate of damage caused by leaf chewers. Therefore, when optimizing the landscape pattern, making a reasonable landscape composition and reducing landscape fragmentation can help maintain a balance between economic development and ecological protection and promote the sustainable development of forests.