To solve the problems of large energy consumption and scarcity of spectrum resources in the traditional Internet of Things （IoT）， a Multiple Input Multiple Output-Ambient Backscatter Communication （MIMO-AmBC） system model which is constructed by an ambient backscatter， a Cooperative Receiver （CRx） and ambient Radio Frequency （RF） source was proposed. First， the system model was analyzed by using the Parasitic Symbiotic Radio （PSR） scheme to derive the Signal-to-Noise Ratio （SNR）. Secondly， the approximate expressions for the ergodic rates of the primary link and the backscatter link were derived， and the maximum expression for the ergodic rate of the backscatter link was obtained. Finally， the proposed system model was compared with the traditional cellular network and Commensal Symbiotic Radio （CSR） scheme. The experimental results verify the correctness of the theoretical derivation and give some meaningful conclusions：1） the backscatter link rate increases with the logarithm of the number of receiving antennas and has nothing to do with the number of transmitting antennas； 2） when the SNR is 10 dB， the sum rate of the PSR scheme is higher than those of the traditional scheme and the CSR scheme by 36.8% and 29.9% respectively. Although the primary link rate of the PSR scheme is 5.5% lower than that of the CSR scheme， the ergodic rate of the backscatter link is 7.7 times higher than that of the CSR scheme， which provides theoretical reference for choosing the AmBC symbiosis scheme for practical applications.
