Black carps ( My lop hary ngodon p i ceus) var ying f rom 5. 6mm to 330. 0mm in to tal length ( n = 370) w ere dissected and measured w ith micro sco py, and then the specimens wer e observed thro ugh light and scanning electr on micro sco pye. The result s wer e as fol low ing: 1. With the gr ow th o f body length, the number o f g ill rakers a nd distance betw een them increa sed. When total le ng th rea ched 141. 0mm, gil l rakers w ere 19 and did not incr ease any mo re. The reg ression equat io n o f distance between g ill rakers( y , mm) to bo dy length ( x, mm) was: y= 0. 0252+ 0. 006 4x( n= 265) , r= 0. 988 5> r 0. 001= 0. 321 1. 2. The size and thickness o f ho rny pad increa sed w ith the gr ow th o f body length. The regressio n equat ion of hor ny pad le ng th ( y, mm) to bo dy length ( x, mm) w as: y= 0. 021 17 0. 060 1x( n= 227) , r= 0. 922 8> r0. 001= 0. 321 1, and the reg ression equat ion o f hor ny pa d thickness ( y , mm) to bo dy length ( x, mm) w as: y= 0. 060 5 0. 024 8x ( n= 215) , r= 0. 970 8> r0. 001= 0. 321 1. 3. When total length w as ar ound 7. 6mm, o rigina l teeth develo ped l ike co ne, and dental formula w as 1, 2/ 2, 1. When total length w as f rom 8. 0mm to 28. 5mm, phary ng eal teeth changed 3 t imes in successio n, and dental f ormula changed f rom 3/ 3 to 4/ 5. It w as ca lled t ra nsit io nal teeth pa ttern. When total le ng th was ove r 31. 5mm, phar yngeal teeth dev eloped and changed constantly . At that age, phary ngeal teeth reached the 5th generat ion as mola r. They w ere ca lled f ixed pat tern teeth, and denta l fo rmula wa s 4/ 5. 4. The fo lds and length o f intest ine length increased too w ith the bo dy length. When to tal length w as f rom 6. 7 mm to 10. 6 mm, intestine w as st raig ht. When to tal leng th w as 17. 0 mm, two intest ine fo lds develo ped. When to tal le ng th w as 24. 0 mm, 4 intest ine folds formed. Whe n total length w as 67. 4mm, ther e wa s 6 intest ine f olds. Af ter tha t, there w as no develo pment . When total leng th wa s f rom 6. 7 mm to 311. 0 mm, the avera ge value o f intenst ine length to body leng th w as 0. 522 3 ? 0. 040 3 to 1. 275 ? 0. 209mm. The relat ive intest ine leng th of adult f ish w as f rom 1. 4 to 1. 5. The fo llow ing quest ions w ere discussed: 1. Feeding characte rist ics o f black car p. 2. The stag e and co rre lat ivity of po st-embry onic dev elopment o f digest ive or gan ' s quant itat ive cha racter s. 3. The relat io nship betw een the deve lopment of quant itativ e char acters o f dig est iv e o rgan and the tr ansformat ion of feeding habit s.