A tube-docking holding device includes a first connector bracket and a second connector bracket. The first connector bracket includes two shells. When the two shells are closed, a first accommodation space is surrounded for fixing a portion of a first connector assembly of a catheter. The second connector bracket includes a base body and a cover body. The base body includes a first inner shell and a first outer shell. The cover body includes a second inner shell and a second outer shell. When the cover body and the base body are closed, the first inner shell and the second inner shell surround and define a second accommodation space for fixing a portion of a second connector assembly of a dialysate tube. An interconnected guiding space is formed between the first inner shell and the first outer shell and between the second inner shell and the second outer shell.