This paper provides six analytical price formulas and one put-call parity for continuous geometric-average European Asian options using risk-neutral valuation and properties of stochastic integral when the price of underlying asset follows the model with time-dependent parameters , i . e. time-dependent riskless interest rate r ( t) , and risk asset has time-dependent expected rate of return μ( t ) , volatility σ( t ) and pays time-dependent dividend yield g ( t) . By adjusting the form of strike price , approximated formulas for fixed- strike continuous arithemtic-average Asian options are also obtained