During the breeding season from March to July in 2012-2014, two nests (1.4% of parasitism rate, n=142) of the Mountain Tailorbird (Orthotomus cuculatus) and one nest (10%, n=10) of the Dark-necked Tailorbird (O. atrogularis) were found to be parasitized by the Plaintive Cuckoo (Cacomantis merulinus) in Nonggang area, Guangxi, Southwestern China. The Mountain Tailorbird was firstly recorded as host species by Plaintive Cuckoo, and both the two tailorbird species were firstly recorded as Plaintive Cuckoo hosts in China. The egg mass and volume of the Plaintive Cuckoo were significantly larger than those of the two tailorbird hosts. Spectra analysis of egg reflectance showed that both background color and spot markings of the cuckoo eggs were much different from its two tailorbird hosts.