Chinese Premier Zhao Ziyang arrived here today on the start of a month-long, 10-nation tour of Africa, marking a new Chinese effort to assert its influence in Third World affairs after years of paying little attention to this continent.

He is the first Chinese premier to visit Egypt, or Africa, for 19 years, and if for no other reason than this his trip is attracting a good deal of attention and speculation as to its motives.

Zhao is scheduled to hold two meetings with President Hosni Mubarak during his four-day stay on subjects including Arab Middle East peace plans, the Nonaligned Movement and Chinese arms and technical assistance for Egypt.

His visit comes against a backdrop of increasing Egyptian diplomatic activity in preparation for the summit of nonaligned nations scheduled for March. It is likely Mubarak will try to gain Zhao's backing for Egypt's stand toward President Reagan's Middle East peace initiative. He has been more supportive of it than most other Arab leaders.

Earlier this month, Chinese leaders in Peking received an Arab League delegation led by King Hussein of Jordan that gained China's backing for the Arab peace plan drawn up in Fez, Morocco, in September.

Mubarak has praised the Arab plan but said it lacks any mechanism for being implemented while the Reagan initiative, calling for the creation of a Palestinian entity in association with Jordan, is more realistic and has a greater chance of serving as a basis of negotiations with Israel.

Before leaving Peking, Zhao spelled out China's policy toward the Palestinian question and the right of Israel to exist in these terms:

"It has been China's consistent stand that if Israel withdraws from occupied Arab lands and restores the national rights of the Palestinian people, including their right to establish a state of their own, on this basis all countries in the Middle East should enjoy the right to independence and existence."

In addition to Middle East peace plans, the two leaders also are likely to discuss the state of the badly fragmented Nonaligned Movement of which Egypt and China were founding members in the early 1950s. After years of isolation because of its signing of a treaty with Israel, Egypt is trying to reassert its right to an active role in the movement.

Egypt and China have had good, if not close, relations since the late president Anwar Sadat broke Egypt's close ties with Moscow in the early 1970s and turned elsewhere for arms and support.

China has sold Egypt about 100 F6 jet fighters, the Chinese version of the Soviet-built MiG19, a wide variety of spare parts for its Soviet equipment and at least one submarine. Whether a new arms deal will be signed during Zhao's visit is not known, but Egypt has been seeking arms from many countries, primarily the United States but also from Western European countries.

Zhao is scheduled to visit Algeria and Morocco before heading for Guinea, Zaire and the Congo in West and Central Africa.

Then he is to go to Zambia, Zimbabwe, Tanzania and Kenya.