In this paper, we study the reliable packet forwarding in Wireless Sensor Networks (WSNs) with the multiple-input multiple-output (MIMO) and orthogonal space time block codes (OSTBC) techniques. The objective is to propose a cross-layer optimized forwarding scheme to maximize the Successful Transmission Rate (STR) while satisfying the given end-to-end energy consumption constraint. The channel coding, energy allocation, and route planning are jointly considered to improve the STR. After formulating the problem as a local stochastic optimization, we propose a low-complexity distributed scheme to reduce the implementation complexity. We show by simulations that the proposed scheme can achieve much higher STR in comparison with existed energy-efficient routing protocols, in which no joint design is considered.