Heath-Jarrow-Morton model is generalized by extending the no-arbitrage drift restriction with nonze-ro instantaneous correlations between volatility factors and setting forward rate volatilities subject to generalized mean-reverting square-root processes and correlated with innovations to forward rates． In the framework above， the dynamics of the term structure under the risk-neutral probability measure are described in terms of a finite number of state variables that jointly follow an affine diffusion process under a certain volatility specification， and a quasi-analytical formula for zero coupon bond prices is derived based on transform techniques． Then the result is further generalized to the case under the actual probability measure through the extended affine market price of risk specification．