The surveys conducted from 1988 to 1991 in Hebei, Henan and Shandong provinces and Beijing area revealed that incidence of black locust mosaic ranged from 4% to 87.5%, generally about 30%. Between 74 black locust mosaic samples inoculated, 37 infected peanut. In the transmission tests, aphid (Aphis craccivora) was able to transmit PSV from black locust mosaic to peanut. PSV disease gradients were often observed from black locust mosaic trees into peanut fields. Monitoring aphid population both on the black locust trees and in peanut fields in Kaifeng in 1990 and 1991 indicated that the peaks of aphid multiplication were observed on black locust trees from the middle of May to early or middle of June, producing alate aphids immigrating into peanut fields. After then PSV infected peanut plants appeared in the peanut fields. No PSV seed transmission was found in the peanut fields in Luanxian and Qianan counties during the surveys in the early growing season in 1990 and 1991. PSV was transmitted at a rate of 0. 025% through the seeds collected from PSV infected peanut plants. Since PSV incidence on peanut is generally very low in the disease nonepidemic years, black locust is considered to be more important as a primary source of PSV for the disease epidemic on peanut than PSV transmission through the peanut seeds.