Under the agreement, CTG would acquire up to 30% of the "equity and shareholder loans" owned by the project's developing company, Moray Offshore Renewable Limited (MORL), a wholly owned subsidiary of EDPR.
The agreement between the two developers coincides with a state visit by China premier Xi Jinping to the UK.
The investment is dependent on the UK government holding a second contracts for difference (CfD) auction, and if the bid for the 1.1GW Moray Firth project is successful.
Upon the announcement of a second auction round, CTG will acquire between 10%-20%. If MORL wins a CfD subsidy, CTG will invest another 10%. EDPR said the 1.1GW project may be divided into phases to make it more competitive in the auction.
A second CfD round remains uncertain but an announcement is expected in the budgetary Autumn Statement by the chancellor George Osborne in November.
The Moray Firth project is located in the North Sea, 22km off Scotland's east coast.
In July, EDPR acquired the 33% stake in MORL previously owned by Repsol. In return, Repsol acquired EDPR's 49% stake in the 784MW Inch Cape offshore project also in Scotland.