Hypothetical reference decoder (HRD) is a mathematical model of a decoder and its input buffer. It represents a set of normative requirements on bitstream for the purpose of avoiding buffer overflow and underflow. In other words, any coded video bitstream shall meet constraints imposed by HRD model. Two HRD models, i.e. the earliest arrival time leaky bucket (EAT- LB) and the constrained arrival time leaky bucket (CAT-LB), have been proposed for the JVT standard jointly developed by ISO/IEC and ITU-T. EAT-LB has the lower initial delay, whereas the CAT-LB model has the lower maximum delay. This paper proposes an improved leaky bucket model called latest arrival time leaky bucket (LAT-LB) so as to achieve the advantages of EAT-LB and CAT-LB simultaneously. The proposed LAT-LB first defines the data transmission schedule according to a set of resume points and stop points, and then derives the HRD parameters according to this schedule. Experimental results demonstrate that the proposed LAT-LB outperforms EAT-LB and CAT-LB in terms of initial delay and maximum delay.