Different wind farm locations with different exploitation environments, the optimal wind turbine (WT) spacing is diverse. This paper investigates the optimal wind turbine layout spacing for aligned offshore wind farm based on the exploitation environment in Hong Kong. A hypothetical offshore wind farm is given in the southeastern water area. Twenty years wind data from 1992-2011 are analyzed as the wind data source. The annual power generation (APG), APG per WT, levelized cost of energy (LCOE) and wind farm efficiency are calculated under different wind turbines layout pattern with the wind turbine layout spacing from 5.0D to 15.0D in the prevailing wind direction (PWD) and 5.0D to 12.0D in the crosswind direction (CWD). The power generation, LCOE and wind farm efficiency are used as the evaluation parameters. Results show that the optimal WT layout patterns happens when the WT spacings are large, especially when they are 12.0D, 14.0D, 14.5D and 15.0D in PWD and 8.5D to 11.5D in CWD. The top ten optimal wind turbine layout patterns are obtained. The maximum wind power potential in Hong Kong offshore is 48.47×10⁸ kWh/year, which is about 11.26 % of the 2012 total annual electricity consumption when the WT layout spacing is 14.0D in PWD and 9.5D in CWD, with a APG in the hypothetical wind farm is 6.33×10⁸ kWh/year, with a LCOE of 1.480HKD/kWh and wind farm efficiency of 87.85%.