The invention relates to an ultra-wide-row and high-precision lead frame electroplating assembly line. The assembly line comprises a first electroplating device (1) and a second electroplating device (2) which are arranged sequentially from front to back; a first covering and pressing belt (1.7) is closely attached to the right half section of a first electroplating mold (1.2); and a second covering and pressing belt (2.7) is closely attached to the left half section of a second electroplating mold (2.2). With the assembly line, traditional overall operation for ultra-wide-row and high-precision lead frames is improved into respective liquid spraying on the left side and the right side, two sides of the belts are uniformly stressed due to the fact that the covering and pressing belts are narrowed, the electroplating effect is good, and the silver leakage phenomenon can be avoided.