In this paper, we propose a 2-dimensional (2D) delay-Doppler span estimation method based on the energy leakage suppression technique for OFDM pulse train radar systems. Unlike the existing methods which aim at resolving multiple target reflections, this estimator focuses on the span of the target on the 2D delay-Doppler plane, i.e., the nearest and furthest boundaries in delay, and the smallest and largest boundaries in Doppler. Through minimizing the 2D delay-Doppler joint energy leakage induced by mis-sampled recovered target response, accurate 2D span estimate can be obtained without estimating each and every delay-Doppler pair. Simulation results are also provided to corroborate the validity of the 2D span estimation method.