The invention discloses an 
immunoassay method for a nano-
colloidal gold marker of 
tadalafil and analogs thereof. The determination method comprises the following steps: 
coupling oximate 
tadalafil with 
bovine serum albumin by adopting an activated ester method, synthesizing artificial 
immunity antigen which is used for immunizing animals, and preparing specific 
tadalafil and analogs thereof; in addition, 
coupling the oximate tadalafil with 
egg albumin to be used for construct an 
immunity detection method; separating, purifying and labeling the tadalafil and analogs thereof to the nano-
colloidal gold, and then respectively curing the tadalafil and analogs detection antibodies thereof and goat-anti-rabbit IgG on a carrier, and adding a detection 
antigen into a detection solution. According to the method, the lowest 
detection limit of the tadalafil and analogs thereof legally added into health products and 
Chinese patent medicines is 10mu g / kg, and the fast detection can be completed within 5 minutes. The method is stable, fast and accurate, and suitable for one-step fast detection on legally added medicines.