Spin ladder compounds Sr14-xCaxCu24O41 (SCCO) single crystals have been grown under different oxygen pressures by an optical floating-zone technique. The effects of oxygen pressure on the crystal growth and properties of SCCO were studied. The SCCO single crystals with x≤8 can be grown in a flowing oxygen atmosphere. But the growth of the SCCO compounds with higher Ca content (x>8) needs higher pressure (0.9 MPa). The single crystals were characterized by means of XRD, EDX and resistivity measurement. High pressure is in favor of forming of higher Ca-doped SCCO single crystals. SCCO single crystals grown under different oxygen pressures have almost the same quality