We propose a parameterized modeling technique for wireless relay networks based on IEEE 802.16j standard operating in non-transparent mode. Our modeling is able to represent the downlink throughput in a concise closed form and thus very useful for predicting the downlink system throughput with a few estimated parameters. The key parameters include α which represents how much portion of the whole data from MR-BS to be transmitted over access link without going through relays (0 ≤ α ≤ 1). Another key parameter is r, which determines how much portion of DL (down link) zone is used for access (0 ≤ r ≤ 1). We also add a parameter θ_i, which determines how much portion of the data to be relayed via RSi (0 ≤ θ_i ≤ 1). Our contribution lies in that our formula can be used to estimate the expected downlink system throughput without going through extensive simulation in the early design stage for IEEE 802.16j relay systems. Optimization can be easily performed using our formula.