The invention discloses a formula of green alga dietary fiber adding traditional Chinese medicine relaxing bowel meal replacement powder. The formula comprises the following raw materials that green algae dietary fiber powder, enzymolysis oat powder, egg powder, whole milk powder, sesame powder, radix puerariae powder, fructus crataegi powder, semen cassiae powder, ormosia powder, cyan dried seaw,radix glycyrrhizae, newtol, thyme and maltodextrin. A preparation method comprises the following steps that S1, radix puerariae, fructus crataegi, semen cassiae and the thyme are taken and boiled with strong fire and slow fire, and pure medicine liquid is obtained; S2, the green algae dietary fiber powder, the cyan dried seaw, the radix glycyrrhizae and the ormosia powder are screened; and S3, the pure medicine liquid obtained in the S1 and powder materials in the S2 are mixed and stirred with the enzymolysis oat powder, the egg powder, the maltodextrin, the sesame powder, the whole milk powder and the newtol by adding water for preparing. The green alga dietary fiber adding traditional Chinese medicine relaxing bowel meal replacement powder is convenient to eat, rich in the dietary fiber, high in protein, low in calorie and complete in nutrients, and further has the effects of reducing blood fat, reducing blood sugar, increasing gastrointestinal function, strengthening spleen and regulating vital energy and relaxing bowel.