The invention relates to a multi-effect distillation seawater desalinating device of a multi-section type condenser, belonging to the technical field of seawater desalinization. The device comprises an evaporator, a condenser, a working steam inlet (1), a working steam condensate water outlet (2), a concentrated seawater connecting pipe (4), a condensed fresh water connecting pipe (5), a concentrated seawater draining pump (9), a fresh water draining pump (10), a secondary steam inlet condensing pipe (11), a seawater inlet (13), a cooling seawater draining port (14) and a seawater inlet branch pipe (16). The invention is characterized in that the condenser is divided into N sections from section 1 to section N, and seawater enters in the multi-section type condenser from the section N to the section 1 which are connected in series; on the basis of an original M-effect evaporator, an N-1-effect evaporator which corresponds to the N-section condenser is additionally arranged on the evaporator; secondary steam coming out of the original M-effect evaporator is divided into two paths and enters the 1-effect condenser and the M+1-effect evaporator in parallel, and so forth,, the secondary steam coming out of the M+N-1-effect evaporator enters the N-effect condenser finally. On the premise of not increasing the quantity of inlet seawater of unit water making quantity, the invention can increase the total temperature difference of the first evaporator and the last evaporator.