The mid-term forecast of daily solar active index is always complex and difficult in space environment forecasting operation. A new 27-day forecast model of 10.7 cm solar radio flux F10.7 index) based on the observation and general evolution of the solar active regions has been built to improve the Auto-Regress (AR) method. The area and longitude of an active region has been used as control parameters in the new model. The sunspot decay rate suggests a simple way to forecast the area of active region in next solar rotation. The new model is tested in the following two cases: (1) F10.7 index is much larger than usual as unexpected solar active regions appear on the disk; (2) F10.7 index becomes quite peaceful because the dominant solar activity regions disappear. The result indicates that the relative errors of the new model were mainly 5%~9 % smaller than those of AR model under these two conditions. That means it is possible to improve the operational forecast model of solar index using the information of solar active regions.