Ostriches reproduce like humans and have the same reproductive organs and they reproduce internally. They have shorts feathers to insulate the body and their legs are modified for running at quick speeds and to fight off predators that might attack them. The whole process of fertilisation is the same. You might wonder what it is. Fertilisation occurs when sexual intercourse allows sperm to travel through the female's vagina through the cervix and the uterus to meet the mature egg. Although males can release 200-300 million sperm, it only takes one to penetrate the egg.
After fertilization in the female's fallopian tube, the nuclei of the sperm and egg fuse to form a new cell (the zygote). This cell contains 46 chromosomes, 23 from each parent cell. As the zygote travels to the uterus, it divides, forming a cluster of cells (the morula) by about 3 days after fertilization.
The morula develops a cavity and is now known as a blastocyst, which will become the embryo. This blastocyst floats freely within the uterine cavity for about 48 hours before attaching itself to a site in the endometrium (uterine lining).
Ostriches are polygamous type. They will mate just before the onset of rainy season in order to ensure plenty of food for the chicks hatched to sustain till they become several months old. For more details refer : http://www.honoluluzoo.org/ostrich.htm