Quasi-two-dimensional hole gas in a strained Si/SixGe1-x/Si quantum well structure is investigated both theoretically and experimentally. The hole effective mass and the charge distribution in the structure are achieved from the self-consistent solution of the Schrodinger-Poisson equations. The band mixing effect with split-off band is included by using the 3 x 3 multiband effective mass model. High quality Si/Si0.8Ge0.2/Si p-type modulation doped quantum well has been grown by molecular beam epitaxy and the electrical properties have been measured at different temperatures. Hole mobility as high as similar to 10,400 cm(2)/V with a sheet carrier concentration of similar to 1.1 x 10(12) and the effective mass of similar to 0.3 m(0) are obtained at T = 4 K. These values are in fairly good agreement with theoretical predictions.