Copper alloy strip and its preparation method

A copper alloy strip, comprising following components in percentage by mass:

• 0.1 wt %-1.0 wt % of Cr, 0.01 wt %-0.2 wt % of Si, 0.01 wt %-1.0 wt % of X and balance of Cu and inevitable impurities, wherein X is at least one of Fe, Ti, Zr, Ag, Zn and Sn;
• on a section of the copper alloy strip perpendicular to a rolling direction, a number of second-phase particles having a particle size of 5 nm or below 5 nm is A, a number of second-phase particles having a particle size of 100 nm or above 100 nm is B, and A/B is greater than or equal to 3,
• wherein a microstructure of the copper alloy strip comprises copper texture and Goss texture, and an area ratio of the copper texture to the Goss texture is controlled at 1.0-3.0.