An automatic analyzer , comprising: a dispensing unit configured to dispense a sample and/or a reagent into a reaction vessel; a reaction unit configured to perform an incubation and a bound-free separation for reactants in the reaction vessel; a measuring unit independent of the reaction unit and configured to measure a reaction signal in the reaction vessel; and a transfer unit configured to transfer the reaction vessel between different positions; wherein the reaction unit comprises a rotation device provided with a reaction vessel holder for holding the reaction vessel; the rotation device is a reaction carousel configured to rotate by a fixed angle at a fixed interval so as to carry the reaction vessel holder of the reaction carousel forward; wherein the measuring unit comprises a measurement carousel provided with a reaction vessel holder for holding the reaction vessel, the reaction vessel holder of the measurement carousel is further provided with a dispensing position to perform the dispensing of the sample and/or the reagent; at least one reaction vessel holder of the reaction carousel and at least one reaction vessel holder of the measurement carousel are in a horizontal movable area of the transfer unit ; wherein the reaction vessel holder of the reaction carousel comprises a first reaction vessel holder configured to transfer the reaction vessel for a bound-free separation and a second reaction vessel holder configured to perform an incubation for the reactants in the reaction vessel; wherein the transfer unit is configured to transfer the reaction vessel among a reaction vessel supply unit , the first reaction vessel holder of the reaction carousel , the second reaction vessel holder of the reaction carousel , the reaction vessel holder of the measurement carousel , and a reaction vessel disposal chute . a dispensing unit configured to dispense a sample and/or a reagent into a reaction vessel; a reaction unit configured to perform an incubation and a bound-free separation for reactants in the reaction vessel; a measuring unit independent of the reaction unit and configured to measure a reaction signal in the reaction vessel; and a transfer unit configured to transfer the reaction vessel between different positions; wherein the reaction unit comprises a rotation device provided with a reaction vessel holder for holding the reaction vessel; the rotation device is a reaction carousel configured to rotate by a fixed angle at a fixed interval so as to carry the reaction vessel holder of the reaction carousel forward; wherein the measuring unit comprises a measurement carousel provided with a reaction vessel holder for holding the reaction vessel, the reaction vessel holder of the measurement carousel is further provided with a dispensing position to perform the dispensing of the sample and/or the reagent; at least one reaction vessel holder of the reaction carousel and at least one reaction vessel holder of the measurement carousel are in a horizontal movable area of the transfer unit ; wherein the reaction vessel holder of the reaction carousel comprises a first reaction vessel holder configured to transfer the reaction vessel for a bound-free separation and a second reaction vessel holder configured to perform an incubation for the reactants in the reaction vessel; wherein the transfer unit is configured to transfer the reaction vessel among a reaction vessel supply unit , the first reaction vessel holder of the reaction carousel , the second reaction vessel holder of the reaction carousel , the reaction vessel holder of the measurement carousel , and a reaction vessel disposal chute . <EOS>