Smart Grid is a new type of energy-based cyber-physical system (CPS) that will provide reliable, secure, and efficient energy transmission and distribution. The way to secure the distributed energy routing process that efficiently utilizes the distributed energy resources and minimizes the energy transmission overhead is essential in smart grid. In this paper, we study the vulnerability of the distributed energy routing process and investigate novel false data injection attacks against the energy routing process. We consider several general attacks, in which the adversary may manipulate the quantity of energy supply, the quantity of energy response, and the link state of energy transmission. The forged data injected by those attacks will cause imbalanced demand and supply, increase the cost for energy distribution, and disrupt the energy distribution. We formally model these attacks and quantitatively analyze their impact on energy distribution. Our evaluation data show that those attacks can effectively disrupt the effectiveness of energy distribution process, causing significant supplied energy loss, energy transmission cost and the number of outage users.