A biological detection device for a toilet water solution includes a mounting portion, a main system, an adjustable support portion and a detection portion. The main system is connected to the mounting portion. The adjustable support portion can be adjusted for its movement in both horizontal and vertical directions and is connected to the mounting portion. The detection portion is connected and linked to the adjustable support portion and includes a light emitting source and an optical sensor. The biological detection device for a toilet water solution is a home healthcare device capable of automatically detecting whether there is blood in stool or urine without adding any chemical reagent or collecting any stool or urine specimen.