The experimental transmission of a recently identified new Theileria (China 1) species pathogenic for sheep and goats in northern China is described. Haemaphysalis qinghaiensis nymphs and adults developed from larvae and nymph engorged on sheep infected with Theileria sp. (China 1) were able to respectively transmit the Theileria sp. to splenectomized sheep. Meanwhile, H. longicornis nymphs and adults developed from larvae and nymphs engorged on sheep infected with Theileria sp. (China 1) were also able to respectively transmit this new Theileria sp. (China 1) to splenectomized sheep. These experiments suggested that the Theileria sp. (China 1) could be transmitted by at least two species of Haemaphysalis sp. ticks, H. longicornis and H. qinghaiensis, and the mode of transmission is stage to stage.