The present invention discloses a combined scalar quantizing method, aiming at that the prior scalar quantizing method leaves statistic correlation among each sampling value of information source out of account, which comprises the following steps: transmitting original variable into middle variable through specific transforming relationship; quantizing the middle variable according to the variance of middle variable to feed back and transmit; restoring the middle variable into original variable through transforming relationship when needing original variable. The present invention also provides level quantizing method of self-adapting modulating scalar, which is fit for different system needs.