The present disclosure relates to an uplink summation method and device, and a distributed antenna system. The method comprises: acquiring uplink CPRI data streams of a channel of an AU or an EU in a system, performing bit width extension on the CPRI data streams, and performing full precision summation; extracting an orthogonal IQ signal in the CPRI data streams after summation, and determining a reference value and a detected value of the IQ signal so as to determine attenuation values corresponding to fast fading and slow amplification of the IQ signal; generating a gain table corresponding to CPRI data according to carrier mapping information of the system and the attenuation values; and shifting the IQ signal in the CPRI data streams according to the gain table, and truncating the shifted IQ signal with a preconfigured bit width.