Holding the hands of two Washington school children, Jihan Sadat and Aliza Begin toured the Capital Children's Museum yesterday morning. The tour was the two women's first appearance together at a nonofficial gathering.

"Let's throw our hands together and work together," said Jihan Sadat, setting a tone of camaraderie and light-heartedness that lasted through the 90-minute visit. Aliza Begin simply replied, "Let's move together."

Last year, on separate visits to the United States, both women had visited the museum, which was then housed in three rooms of an elementary school. The museum is a favorite project of several Carter administration wives and its new home in a spacious converted near Union Station was opened by Rosalynn Carter last month.

"I was just saying to my husband, the last time the museum was just a gleam. Now it is a reality," said Jihan Sadat.

Yesterday Aliza Begin arrived 15 minutes late from an early-morning meeting on Soviet Jewry. While she waited, Jihan Sadat spoke quietly about Monday's historic treaty-signing. "We had a flood of emotions. Everyone who came to shake hands had tears in their eyes," she said. When Aliza Begin arrived, the two women embraced.

With their small personal entourages, and a pushing pack of reporters and cameramen to record this offbeat, personal event, the two women were given the same tour of a Mexican exhibition as the children visitors.

At the end of the tour, Ann White Lewin, the executive director of the museum, spoke of the connection between the Egyptian-Israeli peace treaty and the International Year of the Child. "If we provide examples of harmony and peace, children will accept that as the norm and will strive for peace and value it in their own lives," said Lewin. Both women have expressed interest in starting a similar museum in their own countries.

In the afternoon Jihan Sadat combined her interest in children's health and education by visiting the Howard University Hospital. Her tour, conducted by LaSalle Lefall Jr., president of the American Cancer Society, concentrated on the cancer-treatment and surgical facilities. Since Egypt has one of the highest rates of bladder cancer in the world, she repeatedly inquired how the equipment and treatment affected that particular cancer. At one point she stopped to chat with a dozen Egyptian students and physicians. The conversation in Arabic was punctuated with kisses and hand clasps.