Give priority to child theme stylesheet

Your child theme’s stylesheet will usually be loaded automatically. If it is not, you will need to enqueue it as well. Setting ‘parent-style’ as a dependency will ensure that the child theme stylesheet loads after it.

/**
 * Enqueue theme styles (parent first, child second)
 * 
 */
function wpse218610_theme_styles() {

    $parent_style="parent-style";

    wp_enqueue_style( $parent_style, get_template_directory_uri() . '/woocommerce/woo.css' );
    wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() . '/woocommerce/woo.css', array( $parent_style ) );
}
add_action( 'wp_enqueue_scripts', 'wpse218610_theme_styles' );

Note: take a look in the Theme Developer Handbook for some extra information.