One supercritical pressure varying steam generator can restrain unbalance in outlet temperature of evaporating tubes caused by the unevenly distributed heat load inside boiler and reduce heat stress in boiler ball. The evaporating tubes near the combustor and with large heat absorption are inclined to the vertical line at an angle of 15 deg and the combustor bellows is also inclined correspondingly and separated into two or three sections. The evaporating tubes at the upper and lower parts are laid vertically. Therefore, the evaporating tubes absorb heat homogeneously, have the same number atthe upper, low and central parts owing to the small inclined angles and can support their self weight for simple structure. The combustor with inclined bellows is so mounted to evaporating tubes thatthe heat load is homogeneous.