Disclosed is an intra-cardiac implant, a device and a method for respectively implanting two connected intra-cardiac implants to two cardiac chambers at one time. The intra-cardiac implant comprises a columnar housing including a sidewall, a first terminal and a second terminal, a first connecting portion located at the first terminal of the housing and configured to connect with the implantation device; and a hook body mounted at the sidewall of the housing and comprising a fixed end on the sidewall and a free end stretching from the fixed end, wherein the hook body is configured to form a clamping structure with the sidewall, the free end comprises a tip on its top for piercing the myocardium, and the intra-cardiac implant is clamped between the hook body and the sidewall, so that the intra-cardiac implant is fixed on the myocardium.