This paper is written to assure that the water layers in Tsingtao district are suitable forthe growth of Porphyra yezoensis and Porphyra suborbioulata and to present references for abetter development and a higher production of Porphyra cultivation. The experiments werecarried out from December, 1963 to April, 1964, in the Middle Harbour (中港), Tsingtao. The results obtained are as follows: 1) Porphyra yezocnsis can grow extremely well from December to April in the followingyear. Their increase in volume in the course of 91 days, is from 0.54 cm² to 154.12 cm². 2) The water layers fitting them best in the littoral zone are 0.5-1.5 meter over thestandard level. In these layers they do not only show rapid growth but also show good colours.(The volume increase of plants growing two meters above the Standard level is, within 58days, only one-tenth of that growing one meter above the standard level). The growth of Por-phyra yezoensis is hindered. In the layers of two meters or more above the standard level. Th-eir pigments fade, they turn to be quite pale, and they die off in the end. 3) Porphyra yezoensis which have been growing in littoral zone and have been later tran-splanted into the sea water do not suffer any deterimental effect on their growth. And whatis more, they grow very well in an ever changing weather with no sunlight before the Mouthof March. It is the authors' finding that the layer which suits their growth best is the one thatlies between the surface water and 0.5 m. below. 4) The growth of Por phyra suborbiculcata in the littoral zone is the same as that of porphyrayezoensin.Porphyra suborbiculata growing two meters above the standard level is scarcely existing.The migration of Porphyra suborbioulata from the littoral zone into the sea water favours theirgrowth. The speed of growth becomes much faster. Based upon the experimental results, the authors hold that full attention should be paidto the growing layers of Porphyra duriug their cultivation in the littoral zone, and the authorsdeem it necessary that, in the time the cultivation in the littaral zone is going on. attentionshould also be given to the hanging method of their cultivation in a big scale. Although thegrowth of Porphyra in nature is confined in the littoral zone, it is not correct to considerthe surface layer to be unsuitable for their growth. It is shown by the experimental resultsthat Por phyra raised in the water layers from the surface to 0.5 meter below grow fairly well, especially before March and they over-match those cultivated in the littoral zone. This phe-nomenon is perhaps produced by the relatively stable surroundings , viz. appropriate conditionsof temperature and sunlight. The authors consider it to be desirable to raise Porphyra byhanging method at this depth. The cultivation by hanging method is particularly practicableto spread the cultivation areas. It can be practised in shallow waters which are unsuitablefor the cultivation of Laminaria. The cultivation of Porphyra by the hanging method is alsoan easy job.